20991624948 has 72 divisors (see below), whose sum is σ = 60694425792. Its totient is φ = 5992468992.

The previous prime is 20991624947. The next prime is 20991624967. The reversal of 20991624948 is 84942619902.

20991624948 is a `hidden beast` number, since 2 + 0 + 9 + 9 + 1 + 624 + 9 + 4 + 8 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 20991624894 and 20991624903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20991624943) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 264036 + ... + 334212.

It is an arithmetic number, because the mean of its divisors is an integer number (842978136).

Almost surely, 2^20991624948 is an apocalyptic number.

20991624948 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

20991624948 is an abundant number, since it is smaller than the sum of its proper divisors (39702800844).

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

20991624948 is a wasteful number, since it uses less digits than its factorization.

20991624948 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71381 (or 71376 counting only the distinct ones).

The product of its (nonzero) digits is 2239488, while the sum is 54.

The spelling of 20991624948 in words is "twenty billion, nine hundred ninety-one million, six hundred twenty-four thousand, nine hundred forty-eight".