66681610 has 8 divisors (see below), whose sum is σ = 120026916. Its totient is φ = 26672640.

The previous prime is 66681607. The next prime is 66681613. The reversal of 66681610 is 1618666.

It is an interprime number because it is at equal distance from previous prime (66681607) and next prime (66681613).

It can be written as a sum of positive squares in 2 ways, for example, as 63664441 + 3017169 = 7979^2 + 1737^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×66681610² = 8892874224384200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66681613) 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, 3334071 + ... + 3334090.

Almost surely, 2^66681610 is an apocalyptic number.

66681610 is a deficient number, since it is larger than the sum of its proper divisors (53345306).

66681610 is a wasteful number, since it uses less digits than its factorization.

66681610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6668168.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 66681610 is about 8165.8808465468. The cubic root of 66681610 is about 405.5104268988.

The spelling of 66681610 in words is "sixty-six million, six hundred eighty-one thousand, six hundred ten".