65139991 has 8 divisors (see below), whose sum is σ = 74737440. Its totient is φ = 55615488.

The previous prime is 65139989. The next prime is 65140001. The reversal of 65139991 is 19993156.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 65139991 - 2¹ = 65139989 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 (65139911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16306 + ... + 19903.

It is an arithmetic number, because the mean of its divisors is an integer number (9342180).

Almost surely, 2^65139991 is an apocalyptic number.

65139991 is a deficient number, since it is larger than the sum of its proper divisors (9597449).

65139991 is a wasteful number, since it uses less digits than its factorization.

65139991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36473.

The product of its digits is 65610, while the sum is 43.

The square root of 65139991 is about 8070.9349520362. The cubic root of 65139991 is about 402.3610178178.

The spelling of 65139991 in words is "sixty-five million, one hundred thirty-nine thousand, nine hundred ninety-one".