91905921 has 20 divisors (see below), whose sum is σ = 140489712. Its totient is φ = 59843448.

The previous prime is 91905889. The next prime is 91905923. The reversal of 91905921 is 12950919.

It is not a de Polignac number, because 91905921 - 2⁵ = 91905889 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (91905923) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9711 + ... + 16676.

Almost surely, 2^91905921 is an apocalyptic number.

It is an amenable number.

91905921 is a deficient number, since it is larger than the sum of its proper divisors (48583791).

91905921 is a wasteful number, since it uses less digits than its factorization.

91905921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26442 (or 26433 counting only the distinct ones).

The product of its (nonzero) digits is 7290, while the sum is 36.

The square root of 91905921 is about 9586.7575853361. The cubic root of 91905921 is about 451.2818119955.

The spelling of 91905921 in words is "ninety-one million, nine hundred five thousand, nine hundred twenty-one".