21645002406 has 16 divisors (see below), whose sum is σ = 43620464448. Its totient is φ = 7159924200.

The previous prime is 21645002387. The next prime is 21645002441. The reversal of 21645002406 is 60420054612.

It is a super-2 number, since 2×21645002406² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13768300 + ... + 13769871.

It is an arithmetic number, because the mean of its divisors is an integer number (2726279028).

Almost surely, 2^21645002406 is an apocalyptic number.

21645002406 is an abundant number, since it is smaller than the sum of its proper divisors (21975462042).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21645002406 is a wasteful number, since it uses less digits than its factorization.

21645002406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27538307.

The product of its (nonzero) digits is 11520, while the sum is 30.

The spelling of 21645002406 in words is "twenty-one billion, six hundred forty-five million, two thousand, four hundred six".