65501991 has 12 divisors (see below), whose sum is σ = 94977168. Its totient is φ = 43500384.

The previous prime is 65501971. The next prime is 65502043. The reversal of 65501991 is 19910556.

65501991 is a `hidden beast` number, since 6 + 550 + 19 + 91 = 666.

It is not a de Polignac number, because 65501991 - 2⁵ = 65501959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65501971) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11470 + ... + 16203.

It is an arithmetic number, because the mean of its divisors is an integer number (7914764).

Almost surely, 2^65501991 is an apocalyptic number.

65501991 is a deficient number, since it is larger than the sum of its proper divisors (29475177).

65501991 is a wasteful number, since it uses less digits than its factorization.

65501991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27942 (or 27939 counting only the distinct ones).

The product of its (nonzero) digits is 12150, while the sum is 36.

The square root of 65501991 is about 8093.3300315754. The cubic root of 65501991 is about 403.1049832498.

The spelling of 65501991 in words is "sixty-five million, five hundred one thousand, nine hundred ninety-one".