21286631520 has 960 divisors, whose sum is σ = 95158457856. Its totient is φ = 4352901120.

The previous prime is 21286631477. The next prime is 21286631543. The reversal of 21286631520 is 2513668212.

21286631520 is a `hidden beast` number, since 2 + 12 + 8 + 6 + 631 + 5 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 82827232 + ... + 82827488.

Almost surely, 2^21286631520 is an apocalyptic number.

21286631520 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 21286631520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47579228928).

21286631520 is an abundant number, since it is smaller than the sum of its proper divisors (73871826336).

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

21286631520 is a wasteful number, since it uses less digits than its factorization.

21286631520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21286631520 in words is "twenty-one billion, two hundred eighty-six million, six hundred thirty-one thousand, five hundred twenty".