21761286247872 has 392 divisors, whose sum is σ = 65139982333440. Its totient is φ = 7209533329920.

The previous prime is 21761286247871. The next prime is 21761286247873. The reversal of 21761286247872 is 27874268216712.

21761286247872 is a `hidden beast` number, since 2 + 1 + 7 + 6 + 12 + 86 + 2 + 478 + 72 = 666.

It is an interprime number because it is at equal distance from previous prime (21761286247871) and next prime (21761286247873).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21761286247871) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 8437876279 + ... + 8437878857.

It is an arithmetic number, because the mean of its divisors is an integer number (166173424320).

Almost surely, 2^{21761286247872} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21761286247872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32569991166720).

21761286247872 is an abundant number, since it is smaller than the sum of its proper divisors (43378696085568).

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

21761286247872 is an equidigital number, since it uses as much as digits as its factorization.

21761286247872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3643 (or 3618 counting only the distinct ones).

The product of its digits is 50577408, while the sum is 63.

The spelling of 21761286247872 in words is "twenty-one trillion, seven hundred sixty-one billion, two hundred eighty-six million, two hundred forty-seven thousand, eight hundred seventy-two".