21197606400 has 180 divisors, whose sum is σ = 75860794152. Its totient is φ = 5652664320.

The previous prime is 21197606387. The next prime is 21197606407. The reversal of 21197606400 is 460679112.

21197606400 is a `hidden beast` number, since 2 + 1 + 1 + 9 + 7 + 6 + 0 + 640 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (180).

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 (21197606407) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 23197 + ... + 207203.

Almost surely, 2^21197606400 is an apocalyptic number.

21197606400 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 21197606400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37930397076).

21197606400 is an abundant number, since it is smaller than the sum of its proper divisors (54663187752).

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

21197606400 is a wasteful number, since it uses less digits than its factorization.

21197606400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184041 (or 184017 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The spelling of 21197606400 in words is "twenty-one billion, one hundred ninety-seven million, six hundred six thousand, four hundred".