66981651 has 16 divisors (see below), whose sum is σ = 98664960. Its totient is φ = 40079520.

The previous prime is 66981643. The next prime is 66981743. The reversal of 66981651 is 15618966.

It is a happy number.

It is not a de Polignac number, because 66981651 - 2³ = 66981643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66981611) 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, 10240 + ... + 15453.

It is an arithmetic number, because the mean of its divisors is an integer number (6166560).

Almost surely, 2^66981651 is an apocalyptic number.

66981651 is a deficient number, since it is larger than the sum of its proper divisors (31683309).

66981651 is a wasteful number, since it uses less digits than its factorization.

66981651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25786.

The product of its digits is 77760, while the sum is 42.

The square root of 66981651 is about 8184.2318515545. The cubic root of 66981651 is about 406.1177293727.

The spelling of 66981651 in words is "sixty-six million, nine hundred eighty-one thousand, six hundred fifty-one".