21489993187 has 36 divisors (see below), whose sum is σ = 24721544664. Its totient is φ = 18668931840.

The previous prime is 21489993181. The next prime is 21489993227. The reversal of 21489993187 is 78139998412.

It is not a de Polignac number, because 21489993187 - 2³ = 21489993179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21489993181) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 9943387 + ... + 9945547.

It is an arithmetic number, because the mean of its divisors is an integer number (686709574).

Almost surely, 2^21489993187 is an apocalyptic number.

21489993187 is a deficient number, since it is larger than the sum of its proper divisors (3231551477).

21489993187 is a wasteful number, since it uses less digits than its factorization.

21489993187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2388 (or 2356 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 61.

The spelling of 21489993187 in words is "twenty-one billion, four hundred eighty-nine million, nine hundred ninety-three thousand, one hundred eighty-seven".