66997491 has 24 divisors (see below), whose sum is σ = 100223424. Its totient is φ = 39480480.

The previous prime is 66997487. The next prime is 66997507. The reversal of 66997491 is 19479966.

It is not a de Polignac number, because 66997491 - 2² = 66997487 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66997421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 44436 + ... + 45918.

It is an arithmetic number, because the mean of its divisors is an integer number (4175976).

Almost surely, 2^66997491 is an apocalyptic number.

66997491 is a deficient number, since it is larger than the sum of its proper divisors (33225933).

66997491 is a wasteful number, since it uses less digits than its factorization.

66997491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1571 (or 1534 counting only the distinct ones).

The product of its digits is 734832, while the sum is 51.

The square root of 66997491 is about 8185.1995088697. The cubic root of 66997491 is about 406.1497401185.

The spelling of 66997491 in words is "sixty-six million, nine hundred ninety-seven thousand, four hundred ninety-one".