20400664644 has 48 divisors (see below), whose sum is σ = 53680043200. Its totient is φ = 6698723328.

The previous prime is 20400664601. The next prime is 20400664651. The reversal of 20400664644 is 44646600402.

It is a happy number.

20400664644 is a `hidden beast` number, since 2 + 0 + 4 + 0 + 0 + 6 + 6 + 4 + 644 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 20400664599 and 20400664608.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1402429 + ... + 1416900.

Almost surely, 2^20400664644 is an apocalyptic number.

It is an amenable number.

20400664644 is an abundant number, since it is smaller than the sum of its proper divisors (33279378556).

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

20400664644 is a wasteful number, since it uses less digits than its factorization.

20400664644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2819409 (or 2819401 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 36.

The spelling of 20400664644 in words is "twenty billion, four hundred million, six hundred sixty-four thousand, six hundred forty-four".