21032621 has 4 divisors (see below), whose sum is σ = 22269852. Its totient is φ = 19795392.

The previous prime is 21032593. The next prime is 21032629. The reversal of 21032621 is 12623012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16240900 + 4791721 = 4030^2 + 2189^2 .

It is a cyclic number.

It is not a de Polignac number, because 21032621 - 2²² = 16838317 is a prime.

It is a super-2 number, since 2×21032621² = 884742292259282, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1237213 = 21032621 / (2 + 1 + 0 + 3 + 2 + 6 + 2 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21032621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21032629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 618590 + ... + 618623.

It is an arithmetic number, because the mean of its divisors is an integer number (5567463).

Almost surely, 2^21032621 is an apocalyptic number.

It is an amenable number.

21032621 is a deficient number, since it is larger than the sum of its proper divisors (1237231).

21032621 is a wasteful number, since it uses less digits than its factorization.

21032621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237230.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21032621 is about 4586.1335567120. The cubic root of 21032621 is about 276.0351990744.

Adding to 21032621 its reverse (12623012), we get a palindrome (33655633).

The spelling of 21032621 in words is "twenty-one million, thirty-two thousand, six hundred twenty-one".