21245402891520 has 576 divisors, whose sum is σ = 76173813408000. Its totient is φ = 5606961315840.

The previous prime is 21245402891423. The next prime is 21245402891521. The reversal of 21245402891520 is 2519820454212.

21245402891520 is a `hidden beast` number, since 2 + 1 + 2 + 4 + 5 + 40 + 2 + 89 + 1 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245402891521) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1357612656 + ... + 1357628304.

Almost surely, 2^{21245402891520} is an apocalyptic number.

21245402891520 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 21245402891520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38086906704000).

21245402891520 is an abundant number, since it is smaller than the sum of its proper divisors (54928410516480).

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

21245402891520 is a wasteful number, since it uses less digits than its factorization.

21245402891520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16083 (or 16063 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 45.

The spelling of 21245402891520 in words is "twenty-one trillion, two hundred forty-five billion, four hundred two million, eight hundred ninety-one thousand, five hundred twenty".