66388431 has 8 divisors (see below), whose sum is σ = 90576640. Its totient is φ = 43229592.

The previous prime is 66388429. The next prime is 66388459. The reversal of 66388431 is 13488366.

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

It is not a de Polignac number, because 66388431 - 2¹ = 66388429 is a prime.

It is a super-2 number, since 2×66388431² = 8814847541283522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66388431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66388481) 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, 257191 + ... + 257448.

It is an arithmetic number, because the mean of its divisors is an integer number (11322080).

Almost surely, 2^66388431 is an apocalyptic number.

66388431 is a deficient number, since it is larger than the sum of its proper divisors (24188209).

66388431 is a wasteful number, since it uses less digits than its factorization.

66388431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514685.

The product of its digits is 82944, while the sum is 39.

The square root of 66388431 is about 8147.9096092188. The cubic root of 66388431 is about 404.9152512809.

The spelling of 66388431 in words is "sixty-six million, three hundred eighty-eight thousand, four hundred thirty-one".