215720517660 has 96 divisors (see below), whose sum is σ = 625336891200. Its totient is φ = 55498168320.

The previous prime is 215720517619. The next prime is 215720517671. The reversal of 215720517660 is 66715027512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2194770 + ... + 2290950.

It is an arithmetic number, because the mean of its divisors is an integer number (6513925950).

Almost surely, 2^215720517660 is an apocalyptic number.

215720517660 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 215720517660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (312668445600).

215720517660 is an abundant number, since it is smaller than the sum of its proper divisors (409616373540).

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

215720517660 is a wasteful number, since it uses less digits than its factorization.

215720517660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97511 (or 97509 counting only the distinct ones).

The product of its (nonzero) digits is 176400, while the sum is 42.

The spelling of 215720517660 in words is "two hundred fifteen billion, seven hundred twenty million, five hundred seventeen thousand, six hundred sixty".