21405500465 has 16 divisors (see below), whose sum is σ = 26519961600. Its totient is φ = 16569024960.

The previous prime is 21405500461. The next prime is 21405500489. The reversal of 21405500465 is 56400550412.

It is not a de Polignac number, because 21405500465 - 2² = 21405500461 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21405500461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1301111 + ... + 1317459.

It is an arithmetic number, because the mean of its divisors is an integer number (1657497600).

Almost surely, 2^21405500465 is an apocalyptic number.

It is an amenable number.

21405500465 is a deficient number, since it is larger than the sum of its proper divisors (5114461135).

21405500465 is a wasteful number, since it uses less digits than its factorization.

21405500465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24832.

The product of its (nonzero) digits is 24000, while the sum is 32.

The spelling of 21405500465 in words is "twenty-one billion, four hundred five million, five hundred thousand, four hundred sixty-five".