21951778700 has 72 divisors (see below), whose sum is σ = 50477831712. Its totient is φ = 8257582080.

The previous prime is 21951778699. The next prime is 21951778747. The reversal of 21951778700 is 787715912.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2465657 + ... + 2474543.

It is an arithmetic number, because the mean of its divisors is an integer number (701080996).

Almost surely, 2^21951778700 is an apocalyptic number.

21951778700 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 21951778700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25238915856).

21951778700 is an abundant number, since it is smaller than the sum of its proper divisors (28526053012).

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

21951778700 is a wasteful number, since it uses less digits than its factorization.

21951778700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10371 (or 10364 counting only the distinct ones).

The product of its (nonzero) digits is 246960, while the sum is 47.

The spelling of 21951778700 in words is "twenty-one billion, nine hundred fifty-one million, seven hundred seventy-eight thousand, seven hundred".