21365971858 has 96 divisors (see below), whose sum is σ = 43655692608. Its totient is φ = 7726924800.

The previous prime is 21365971853. The next prime is 21365971871. The reversal of 21365971858 is 85817956312.

It is a junction number, because it is equal to n+sod(n) for n = 21365971799 and 21365971808.

It is not an unprimeable number, because it can be changed into a prime (21365971853) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1329813 + ... + 1345783.

It is an arithmetic number, because the mean of its divisors is an integer number (454746798).

Almost surely, 2^21365971858 is an apocalyptic number.

21365971858 is an abundant number, since it is smaller than the sum of its proper divisors (22289720750).

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

21365971858 is a wasteful number, since it uses less digits than its factorization.

21365971858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16088 (or 16081 counting only the distinct ones).

The product of its digits is 3628800, while the sum is 55.

The spelling of 21365971858 in words is "twenty-one billion, three hundred sixty-five million, nine hundred seventy-one thousand, eight hundred fifty-eight".