21620465 has 4 divisors (see below), whose sum is σ = 25944564. Its totient is φ = 17296368.

The previous prime is 21620453. The next prime is 21620471. The reversal of 21620465 is 56402612.

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 13366336 + 8254129 = 3656^2 + 2873^2 .

It is a cyclic number.

It is not a de Polignac number, because 21620465 - 2¹² = 21616369 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2162042 + ... + 2162051.

It is an arithmetic number, because the mean of its divisors is an integer number (6486141).

Almost surely, 2^21620465 is an apocalyptic number.

It is an amenable number.

21620465 is a deficient number, since it is larger than the sum of its proper divisors (4324099).

21620465 is an equidigital number, since it uses as much as digits as its factorization.

21620465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4324098.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21620465 is about 4649.7811776470. The cubic root of 21620465 is about 278.5832560646.

The spelling of 21620465 in words is "twenty-one million, six hundred twenty thousand, four hundred sixty-five".