21008678400 has 600 divisors, whose sum is σ = 81227394864. Its totient is φ = 5352652800.

The previous prime is 21008678399. The next prime is 21008678401. The reversal of 21008678400 is 487680012.

21008678400 is a `hidden beast` number, since 2 + 100 + 86 + 78 + 400 = 666.

It is an interprime number because it is at equal distance from previous prime (21008678399) and next prime (21008678401).

It is a tau number, because it is divible by the number of its divisors (600).

It is a super-2 number, since 2×21008678400² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008678401) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 23845960 + ... + 23846840.

Almost surely, 2^21008678400 is an apocalyptic number.

21008678400 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 21008678400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40613697432).

21008678400 is an abundant number, since it is smaller than the sum of its proper divisors (60218716464).

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

21008678400 is an equidigital number, since it uses as much as digits as its factorization.

21008678400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944 (or 914 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The spelling of 21008678400 in words is "twenty-one billion, eight million, six hundred seventy-eight thousand, four hundred".