21154820400 has 1440 divisors, whose sum is σ = 98440842240. Its totient is φ = 4087480320.

The previous prime is 21154820399. The next prime is 21154820431. The reversal of 21154820400 is 402845112.

21154820400 is a `hidden beast` number, since 211 + 5 + 48 + 2 + 0 + 400 = 666.

It is a super-5 number, since 5×21154820400⁵ (a number of 53 digits) contains 55555 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 187210744 + ... + 187210856.

It is an arithmetic number, because the mean of its divisors is an integer number (68361696).

Almost surely, 2^21154820400 is an apocalyptic number.

21154820400 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 21154820400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49220421120).

21154820400 is an abundant number, since it is smaller than the sum of its proper divisors (77286021840).

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

21154820400 is a wasteful number, since it uses less digits than its factorization.

21154820400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203 (or 189 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 27.

The spelling of 21154820400 in words is "twenty-one billion, one hundred fifty-four million, eight hundred twenty thousand, four hundred".