91978745 has 4 divisors (see below), whose sum is σ = 110374500. Its totient is φ = 73582992.

The previous prime is 91978717. The next prime is 91978751. The reversal of 91978745 is 54787919.

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 37100281 + 54878464 = 6091^2 + 7408^2 .

It is a cyclic number.

It is not a de Polignac number, because 91978745 - 2⁸ = 91978489 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91978693 and 91978702.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9197870 + ... + 9197879.

It is an arithmetic number, because the mean of its divisors is an integer number (27593625).

Almost surely, 2^91978745 is an apocalyptic number.

It is an amenable number.

91978745 is a deficient number, since it is larger than the sum of its proper divisors (18395755).

91978745 is a wasteful number, since it uses less digits than its factorization.

91978745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18395754.

The product of its digits is 635040, while the sum is 50.

The square root of 91978745 is about 9590.5549891547. The cubic root of 91978745 is about 451.4009754106.

The spelling of 91978745 in words is "ninety-one million, nine hundred seventy-eight thousand, seven hundred forty-five".