21637449945 has 64 divisors (see below), whose sum is σ = 40726022400. Its totient is φ = 10869189120.

The previous prime is 21637449943. The next prime is 21637449961. The reversal of 21637449945 is 54994473612.

21637449945 is a `hidden beast` number, since 21 + 63 + 74 + 499 + 4 + 5 = 666.

It is not a de Polignac number, because 21637449945 - 2¹ = 21637449943 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21637449891 and 21637449900.

It is not an unprimeable number, because it can be changed into a prime (21637449943) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 419365 + ... + 468125.

It is an arithmetic number, because the mean of its divisors is an integer number (636344100).

Almost surely, 2^21637449945 is an apocalyptic number.

It is an amenable number.

21637449945 is a deficient number, since it is larger than the sum of its proper divisors (19088572455).

21637449945 is a wasteful number, since it uses less digits than its factorization.

21637449945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48967 (or 48961 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 54.

The spelling of 21637449945 in words is "twenty-one billion, six hundred thirty-seven million, four hundred forty-nine thousand, nine hundred forty-five".