21638145600 has 420 divisors, whose sum is σ = 80031336000. Its totient is φ = 5734333440.

The previous prime is 21638145577. The next prime is 21638145623. The reversal of 21638145600 is 654183612.

It is a happy number.

21638145600 is a `hidden beast` number, since 2 + 1 + 6 + 3 + 8 + 1 + 45 + 600 = 666.

It is an interprime number because it is at equal distance from previous prime (21638145577) and next prime (21638145623).

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 59 ways as a sum of consecutive naturals, for example, 25789981 + ... + 25790819.

It is an arithmetic number, because the mean of its divisors is an integer number (190550800).

Almost surely, 2^21638145600 is an apocalyptic number.

21638145600 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 21638145600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40015668000).

21638145600 is an abundant number, since it is smaller than the sum of its proper divisors (58393190400).

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

21638145600 is a wasteful number, since it uses less digits than its factorization.

21638145600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072 (or 1048 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21638145600 in words is "twenty-one billion, six hundred thirty-eight million, one hundred forty-five thousand, six hundred".