21521461 has 4 divisors (see below), whose sum is σ = 23176972. Its totient is φ = 19865952.

The previous prime is 21521459. The next prime is 21521483. The reversal of 21521461 is 16412512.

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 1674436 + 19847025 = 1294^2 + 4455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21521461 - 2¹ = 21521459 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 827736 + ... + 827761.

It is an arithmetic number, because the mean of its divisors is an integer number (5794243).

Almost surely, 2^21521461 is an apocalyptic number.

It is an amenable number.

21521461 is a deficient number, since it is larger than the sum of its proper divisors (1655511).

21521461 is a wasteful number, since it uses less digits than its factorization.

21521461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655510.

The product of its digits is 480, while the sum is 22.

The square root of 21521461 is about 4639.1228696813. The cubic root of 21521461 is about 278.1573777229.

Adding to 21521461 its reverse (16412512), we get a palindrome (37933973).

The spelling of 21521461 in words is "twenty-one million, five hundred twenty-one thousand, four hundred sixty-one".