21123698400 has 1296 divisors, whose sum is σ = 95339147904. Its totient is φ = 4467778560.

The previous prime is 21123698383. The next prime is 21123698423. The reversal of 21123698400 is 489632112.

21123698400 is a `hidden beast` number, since 2 + 11 + 236 + 9 + 8 + 400 = 666.

It is a tau number, because it is divible by the number of its divisors (1296).

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 215 ways as a sum of consecutive naturals, for example, 491248779 + ... + 491248821.

Almost surely, 2^21123698400 is an apocalyptic number.

21123698400 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 21123698400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47669573952).

21123698400 is an abundant number, since it is smaller than the sum of its proper divisors (74215449504).

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

21123698400 is a wasteful number, since it uses less digits than its factorization.

21123698400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 79 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The spelling of 21123698400 in words is "twenty-one billion, one hundred twenty-three million, six hundred ninety-eight thousand, four hundred".