21513522400 has 144 divisors (see below), whose sum is σ = 54673844400. Its totient is φ = 8256245760.

The previous prime is 21513522367. The next prime is 21513522421. The reversal of 21513522400 is 422531512.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3778756 + ... + 3784444.

It is an arithmetic number, because the mean of its divisors is an integer number (379679475).

Almost surely, 2^21513522400 is an apocalyptic number.

21513522400 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 21513522400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27336922200).

21513522400 is an abundant number, since it is smaller than the sum of its proper divisors (33160322000).

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

21513522400 is a wasteful number, since it uses less digits than its factorization.

21513522400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5901 (or 5888 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

The spelling of 21513522400 in words is "twenty-one billion, five hundred thirteen million, five hundred twenty-two thousand, four hundred".