66659997 has 4 divisors (see below), whose sum is σ = 88880000. Its totient is φ = 44439996.

The previous prime is 66659993. The next prime is 66660059. The reversal of 66659997 is 79995666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66659997 - 2² = 66659993 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66659993) 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, 11109997 + ... + 11110002.

It is an arithmetic number, because the mean of its divisors is an integer number (22220000).

Almost surely, 2^66659997 is an apocalyptic number.

It is an amenable number.

66659997 is a deficient number, since it is larger than the sum of its proper divisors (22220003).

66659997 is a wasteful number, since it uses less digits than its factorization.

66659997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22220002.

The product of its digits is 5511240, while the sum is 57.

The square root of 66659997 is about 8164.5573670592. The cubic root of 66659997 is about 405.4666105006.

The spelling of 66659997 in words is "sixty-six million, six hundred fifty-nine thousand, nine hundred ninety-seven".