20438644644 has 36 divisors (see below), whose sum is σ = 56361112080. Its totient is φ = 6193528560.

The previous prime is 20438644591. The next prime is 20438644661. The reversal of 20438644644 is 44644683402.

20438644644 is a `hidden beast` number, since 204 + 386 + 4 + 4 + 64 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20438644644.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25805974 + ... + 25806765.

Almost surely, 2^20438644644 is an apocalyptic number.

It is an amenable number.

20438644644 is an abundant number, since it is smaller than the sum of its proper divisors (35922467436).

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

20438644644 is a wasteful number, since it uses less digits than its factorization.

20438644644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51612760 (or 51612755 counting only the distinct ones).

The product of its (nonzero) digits is 1769472, while the sum is 45.

The spelling of 20438644644 in words is "twenty billion, four hundred thirty-eight million, six hundred forty-four thousand, six hundred forty-four".