91621945 has 4 divisors (see below), whose sum is σ = 109946340. Its totient is φ = 73297552.

The previous prime is 91621931. The next prime is 91621961. The reversal of 91621945 is 54912619.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18826921 + 72795024 = 4339^2 + 8532^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91621945 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9162190 + ... + 9162199.

It is an arithmetic number, because the mean of its divisors is an integer number (27486585).

Almost surely, 2^91621945 is an apocalyptic number.

It is an amenable number.

91621945 is a deficient number, since it is larger than the sum of its proper divisors (18324395).

91621945 is a wasteful number, since it uses less digits than its factorization.

91621945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18324394.

The product of its digits is 19440, while the sum is 37.

The square root of 91621945 is about 9571.9352797645. The cubic root of 91621945 is about 450.8165339477.

The spelling of 91621945 in words is "ninety-one million, six hundred twenty-one thousand, nine hundred forty-five".