21779947500 has 120 divisors (see below), whose sum is σ = 63810124224. Its totient is φ = 5780040000.

The previous prime is 21779947493. The next prime is 21779947573. The reversal of 21779947500 is 574997712.

It is a super-2 number, since 2×21779947500² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1575619 + ... + 1589381.

Almost surely, 2^21779947500 is an apocalyptic number.

21779947500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21779947500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31905062112).

21779947500 is an abundant number, since it is smaller than the sum of its proper divisors (42030176724).

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

21779947500 is a wasteful number, since it uses less digits than its factorization.

21779947500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14001 (or 13984 counting only the distinct ones).

The product of its (nonzero) digits is 1111320, while the sum is 51.

The spelling of 21779947500 in words is "twenty-one billion, seven hundred seventy-nine million, nine hundred forty-seven thousand, five hundred".