65691381 has 32 divisors (see below), whose sum is σ = 105043968. Its totient is φ = 35703360.

The previous prime is 65691377. The next prime is 65691397. The reversal of 65691381 is 18319656.

It is not a de Polignac number, because 65691381 - 2² = 65691377 is a prime.

It is a super-2 number, since 2×65691381² = 8630715075374322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65691331) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 133546 + ... + 134036.

It is an arithmetic number, because the mean of its divisors is an integer number (3282624).

Almost surely, 2^65691381 is an apocalyptic number.

It is an amenable number.

65691381 is a deficient number, since it is larger than the sum of its proper divisors (39352587).

65691381 is a wasteful number, since it uses less digits than its factorization.

65691381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 801.

The product of its digits is 38880, while the sum is 39.

The square root of 65691381 is about 8105.0219617223. The cubic root of 65691381 is about 403.4931169546.

The spelling of 65691381 in words is "sixty-five million, six hundred ninety-one thousand, three hundred eighty-one".