21085617600 has 336 divisors, whose sum is σ = 78659370240. Its totient is φ = 5491584000.

The previous prime is 21085617587. The next prime is 21085617653. The reversal of 21085617600 is 671658012.

21085617600 is a `hidden beast` number, since 21 + 0 + 8 + 561 + 76 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1851925 + ... + 1863275.

Almost surely, 2^21085617600 is an apocalyptic number.

21085617600 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 21085617600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39329685120).

21085617600 is an abundant number, since it is smaller than the sum of its proper divisors (57573752640).

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

21085617600 is a wasteful number, since it uses less digits than its factorization.

21085617600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11425 (or 11404 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The spelling of 21085617600 in words is "twenty-one billion, eighty-five million, six hundred seventeen thousand, six hundred".