91771951 has 4 divisors (see below), whose sum is σ = 94252312. Its totient is φ = 89291592.

The previous prime is 91771903. The next prime is 91771961. The reversal of 91771951 is 15917719.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15917719 = 983 ⋅16193.

It is a cyclic number.

It is not a de Polignac number, because 91771951 - 2¹¹ = 91769903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91771961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1240125 + ... + 1240198.

It is an arithmetic number, because the mean of its divisors is an integer number (23563078).

Almost surely, 2^91771951 is an apocalyptic number.

91771951 is a deficient number, since it is larger than the sum of its proper divisors (2480361).

91771951 is a wasteful number, since it uses less digits than its factorization.

91771951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2480360.

The product of its digits is 19845, while the sum is 40.

The square root of 91771951 is about 9579.7677946806. The cubic root of 91771951 is about 451.0624295956.

The spelling of 91771951 in words is "ninety-one million, seven hundred seventy-one thousand, nine hundred fifty-one".