21401515520 has 160 divisors (see below), whose sum is σ = 63975833856. Its totient is φ = 6670540800.

The previous prime is 21401515459. The next prime is 21401515547. The reversal of 21401515520 is 2551510412.

It is a tau number, because it is divible by the number of its divisors (160).

It is a self number, because there is not a number n which added to its sum of digits gives 21401515520.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 142835 + ... + 251405.

Almost surely, 2^21401515520 is an apocalyptic number.

21401515520 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 21401515520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31987916928).

21401515520 is an abundant number, since it is smaller than the sum of its proper divisors (42574318336).

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

21401515520 is a wasteful number, since it uses less digits than its factorization.

21401515520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108612 (or 108596 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 26.

The spelling of 21401515520 in words is "twenty-one billion, four hundred one million, five hundred fifteen thousand, five hundred twenty".