66997990 has 48 divisors (see below), whose sum is σ = 129643632. Its totient is φ = 24919488.

The previous prime is 66997979. The next prime is 66998027. The reversal of 66997990 is 9979966.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 241732 + ... + 242008.

It is an arithmetic number, because the mean of its divisors is an integer number (2700909).

Almost surely, 2^66997990 is an apocalyptic number.

66997990 is a deficient number, since it is larger than the sum of its proper divisors (62645642).

66997990 is a wasteful number, since it uses less digits than its factorization.

66997990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389 (or 370 counting only the distinct ones).

The product of its (nonzero) digits is 1653372, while the sum is 55.

The square root of 66997990 is about 8185.2299906600. The cubic root of 66997990 is about 406.1507484559.

It can be divided in two parts, 6 and 6997990, that added together give a palindrome (6997996).

The spelling of 66997990 in words is "sixty-six million, nine hundred ninety-seven thousand, nine hundred ninety".