21506201306465 has 16 divisors (see below), whose sum is σ = 25978819301760. Its totient is φ = 17090713324800.

The previous prime is 21506201306459. The next prime is 21506201306563. The reversal of 21506201306465 is 56460310260512.

It is a happy number.

It is not a de Polignac number, because 21506201306465 - 2²⁸ = 21505932871009 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, 47649182 + ... + 48098408.

It is an arithmetic number, because the mean of its divisors is an integer number (1623676206360).

Almost surely, 2^{21506201306465} is an apocalyptic number.

It is an amenable number.

21506201306465 is a deficient number, since it is larger than the sum of its proper divisors (4472617995295).

21506201306465 is a wasteful number, since it uses less digits than its factorization.

21506201306465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512792.

The product of its (nonzero) digits is 259200, while the sum is 41.

Adding to 21506201306465 its reverse (56460310260512), we get a palindrome (77966511566977).

The spelling of 21506201306465 in words is "twenty-one trillion, five hundred six billion, two hundred one million, three hundred six thousand, four hundred sixty-five".