91981563 has 8 divisors (see below), whose sum is σ = 122990928. Its totient is φ = 61146624.

The previous prime is 91981559. The next prime is 91981567. The reversal of 91981563 is 36518919.

It is an interprime number because it is at equal distance from previous prime (91981559) and next prime (91981567).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91981563 - 2² = 91981559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91981567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42370 + ... + 44487.

It is an arithmetic number, because the mean of its divisors is an integer number (15373866).

Almost surely, 2^91981563 is an apocalyptic number.

91981563 is a deficient number, since it is larger than the sum of its proper divisors (31009365).

91981563 is a wasteful number, since it uses less digits than its factorization.

91981563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87213.

The product of its digits is 58320, while the sum is 42.

The square root of 91981563 is about 9590.7019034062. The cubic root of 91981563 is about 451.4055852979.

The spelling of 91981563 in words is "ninety-one million, nine hundred eighty-one thousand, five hundred sixty-three".