20991629187 has 24 divisors (see below), whose sum is σ = 30572917440. Its totient is φ = 13878743040.

The previous prime is 20991629177. The next prime is 20991629201. The reversal of 20991629187 is 78192619902.

20991629187 is a `hidden beast` number, since 2 + 0 + 9 + 9 + 1 + 629 + 1 + 8 + 7 = 666.

It is not a de Polignac number, because 20991629187 - 2⁴ = 20991629171 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20991629177) 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, 509862 + ... + 549492.

It is an arithmetic number, because the mean of its divisors is an integer number (1273871560).

Almost surely, 2^20991629187 is an apocalyptic number.

20991629187 is a deficient number, since it is larger than the sum of its proper divisors (9581288253).

20991629187 is a wasteful number, since it uses less digits than its factorization.

20991629187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40123 (or 40120 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The spelling of 20991629187 in words is "twenty billion, nine hundred ninety-one million, six hundred twenty-nine thousand, one hundred eighty-seven".