21261465600 has 288 divisors, whose sum is σ = 70835310000. Its totient is φ = 5625610240.

The previous prime is 21261465587. The next prime is 21261465607. The reversal of 21261465600 is 656416212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261465607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22885936 + ... + 22886864.

Almost surely, 2^21261465600 is an apocalyptic number.

21261465600 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 21261465600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35417655000).

21261465600 is an abundant number, since it is smaller than the sum of its proper divisors (49573844400).

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

21261465600 is a wasteful number, since it uses less digits than its factorization.

21261465600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1113 (or 1088 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

The spelling of 21261465600 in words is "twenty-one billion, two hundred sixty-one million, four hundred sixty-five thousand, six hundred".