66961715 has 4 divisors (see below), whose sum is σ = 80354064. Its totient is φ = 53569368.

The previous prime is 66961693. The next prime is 66961799. The reversal of 66961715 is 51716966.

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 66961715 - 2⁸ = 66961459 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6696167 + ... + 6696176.

It is an arithmetic number, because the mean of its divisors is an integer number (20088516).

Almost surely, 2^66961715 is an apocalyptic number.

66961715 is a deficient number, since it is larger than the sum of its proper divisors (13392349).

66961715 is a wasteful number, since it uses less digits than its factorization.

66961715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13392348.

The product of its digits is 68040, while the sum is 41.

The square root of 66961715 is about 8183.0138091048. The cubic root of 66961715 is about 406.0774339270.

It can be divided in two parts, 66961 and 715, that added together give a palindrome (67676).

The spelling of 66961715 in words is "sixty-six million, nine hundred sixty-one thousand, seven hundred fifteen".