66231861 has 16 divisors (see below), whose sum is σ = 89652288. Its totient is φ = 43488000.

The previous prime is 66231857. The next prime is 66231871. The reversal of 66231861 is 16813266.

It is not a de Polignac number, because 66231861 - 2² = 66231857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66231811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72570 + ... + 73476.

It is an arithmetic number, because the mean of its divisors is an integer number (5603268).

Almost surely, 2^66231861 is an apocalyptic number.

It is an amenable number.

66231861 is a deficient number, since it is larger than the sum of its proper divisors (23420427).

66231861 is a wasteful number, since it uses less digits than its factorization.

66231861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1252.

The product of its digits is 10368, while the sum is 33.

The square root of 66231861 is about 8138.2959518563. The cubic root of 66231861 is about 404.5966843050.

It can be divided in two parts, 662 and 31861, that added together give a palindrome (32523).

The spelling of 66231861 in words is "sixty-six million, two hundred thirty-one thousand, eight hundred sixty-one".