215901355978 has 72 divisors (see below), whose sum is σ = 433743043104. Its totient is φ = 79690035600.

The previous prime is 215901355927. The next prime is 215901356057. The reversal of 215901355978 is 879553109512.

It is a happy number.

It is a super-2 number, since 2×215901355978² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 111763 + ... + 666553.

It is an arithmetic number, because the mean of its divisors is an integer number (6024208932).

Almost surely, 2^215901355978 is an apocalyptic number.

215901355978 is an abundant number, since it is smaller than the sum of its proper divisors (217841687126).

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

215901355978 is a wasteful number, since it uses less digits than its factorization.

215901355978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554856 (or 554830 counting only the distinct ones).

The product of its (nonzero) digits is 3402000, while the sum is 55.

The spelling of 215901355978 in words is "two hundred fifteen billion, nine hundred one million, three hundred fifty-five thousand, nine hundred seventy-eight".