21506465 has 16 divisors (see below), whose sum is σ = 26516160. Its totient is φ = 16739520.

The previous prime is 21506453. The next prime is 21506473. The reversal of 21506465 is 56460512.

It is not a de Polignac number, because 21506465 - 2⁸ = 21506209 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32306 + ... + 32964.

It is an arithmetic number, because the mean of its divisors is an integer number (1657260).

Almost surely, 2^21506465 is an apocalyptic number.

It is an amenable number.

21506465 is a deficient number, since it is larger than the sum of its proper divisors (5009695).

21506465 is a wasteful number, since it uses less digits than its factorization.

21506465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 21506465 is about 4637.5063342275. The cubic root of 21506465 is about 278.0927566880.

Adding to 21506465 its reverse (56460512), we get a palindrome (77966977).

The spelling of 21506465 in words is "twenty-one million, five hundred six thousand, four hundred sixty-five".