66881731 has 4 divisors (see below), whose sum is σ = 76436272. Its totient is φ = 57327192.

The previous prime is 66881719. The next prime is 66881747. The reversal of 66881731 is 13718866.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66881731 - 2⁵ = 66881699 is a prime.

It is a super-2 number, since 2×66881731² = 8946331883112722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66881761) 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, 4777260 + ... + 4777273.

It is an arithmetic number, because the mean of its divisors is an integer number (19109068).

Almost surely, 2^66881731 is an apocalyptic number.

66881731 is a deficient number, since it is larger than the sum of its proper divisors (9554541).

66881731 is an equidigital number, since it uses as much as digits as its factorization.

66881731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9554540.

The product of its digits is 48384, while the sum is 40.

The square root of 66881731 is about 8178.1251518915. The cubic root of 66881731 is about 405.9156865857.

The spelling of 66881731 in words is "sixty-six million, eight hundred eighty-one thousand, seven hundred thirty-one".