21099772057 has 24 divisors (see below), whose sum is σ = 26827253376. Its totient is φ = 16445122848.

The previous prime is 21099772051. The next prime is 21099772157. The reversal of 21099772057 is 75027799012.

It is not a de Polignac number, because 21099772057 - 2⁷ = 21099771929 is a prime.

It is a super-2 number, since 2×21099772057² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a self number, because there is not a number n which added to its sum of digits gives 21099772057.

It is not an unprimeable number, because it can be changed into a prime (21099772051) 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, 204513 + ... + 289870.

It is an arithmetic number, because the mean of its divisors is an integer number (1117802224).

Almost surely, 2^21099772057 is an apocalyptic number.

It is an amenable number.

21099772057 is a deficient number, since it is larger than the sum of its proper divisors (5727481319).

21099772057 is a wasteful number, since it uses less digits than its factorization.

21099772057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494477 (or 494470 counting only the distinct ones).

The product of its (nonzero) digits is 555660, while the sum is 49.

The spelling of 21099772057 in words is "twenty-one billion, ninety-nine million, seven hundred seventy-two thousand, fifty-seven".