91918508381 has 16 divisors (see below), whose sum is σ = 106259454720. Its totient is φ = 77880485760.

The previous prime is 91918508221. The next prime is 91918508449. The reversal of 91918508381 is 18380581919.

It is a happy number.

It is not a de Polignac number, because 91918508381 - 2²² = 91914314077 is a prime.

It is a super-2 number, since 2×91918508381² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91918508081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2477951 + ... + 2514771.

It is an arithmetic number, because the mean of its divisors is an integer number (6641215920).

Almost surely, 2^91918508381 is an apocalyptic number.

It is an amenable number.

91918508381 is a deficient number, since it is larger than the sum of its proper divisors (14340946339).

91918508381 is a wasteful number, since it uses less digits than its factorization.

91918508381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40924.

The product of its (nonzero) digits is 622080, while the sum is 53.

The spelling of 91918508381 in words is "ninety-one billion, nine hundred eighteen million, five hundred eight thousand, three hundred eighty-one".