21137502400 has 252 divisors, whose sum is σ = 61656821568. Its totient is φ = 7109007360.

The previous prime is 21137502391. The next prime is 21137502433. The reversal of 21137502400 is 420573112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4152657 + ... + 4157743.

Almost surely, 2^21137502400 is an apocalyptic number.

21137502400 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 21137502400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30828410784).

21137502400 is an abundant number, since it is smaller than the sum of its proper divisors (40519319168).

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

21137502400 is a wasteful number, since it uses less digits than its factorization.

21137502400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5176 (or 5154 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The spelling of 21137502400 in words is "twenty-one billion, one hundred thirty-seven million, five hundred two thousand, four hundred".