21051372187 has 16 divisors (see below), whose sum is σ = 22474755072. Its totient is φ = 19648844800.

The previous prime is 21051372179. The next prime is 21051372193. The reversal of 21051372187 is 78127315012.

It is not a de Polignac number, because 21051372187 - 2³ = 21051372179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21051372137) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2676753 + ... + 2684605.

It is an arithmetic number, because the mean of its divisors is an integer number (1404672192).

Almost surely, 2^21051372187 is an apocalyptic number.

21051372187 is a deficient number, since it is larger than the sum of its proper divisors (1423382885).

21051372187 is a wasteful number, since it uses less digits than its factorization.

21051372187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9158.

The product of its (nonzero) digits is 23520, while the sum is 37.

Adding to 21051372187 its reverse (78127315012), we get a palindrome (99178687199).

The spelling of 21051372187 in words is "twenty-one billion, fifty-one million, three hundred seventy-two thousand, one hundred eighty-seven".