21034651 has 4 divisors (see below), whose sum is σ = 22946904. Its totient is φ = 19122400.

The previous prime is 21034613. The next prime is 21034667. The reversal of 21034651 is 15643012.

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

It is not a de Polignac number, because 21034651 - 2²³ = 12646043 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21034751) 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, 956110 + ... + 956131.

It is an arithmetic number, because the mean of its divisors is an integer number (5736726).

Almost surely, 2^21034651 is an apocalyptic number.

21034651 is a deficient number, since it is larger than the sum of its proper divisors (1912253).

21034651 is a wasteful number, since it uses less digits than its factorization.

21034651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1912252.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21034651 is about 4586.3548707007. The cubic root of 21034651 is about 276.0440794612.

Adding to 21034651 its reverse (15643012), we get a palindrome (36677663).

The spelling of 21034651 in words is "twenty-one million, thirty-four thousand, six hundred fifty-one".