666442551 has 16 divisors (see below), whose sum is σ = 942271488. Its totient is φ = 417532800.

The previous prime is 666442531. The next prime is 666442561. The reversal of 666442551 is 155244666.

It is not a de Polignac number, because 666442551 - 2⁵ = 666442519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666442531) 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, 25786 + ... + 44696.

It is an arithmetic number, because the mean of its divisors is an integer number (58891968).

Almost surely, 2^666442551 is an apocalyptic number.

666442551 is a deficient number, since it is larger than the sum of its proper divisors (275828937).

666442551 is a wasteful number, since it uses less digits than its factorization.

666442551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19622.

The product of its digits is 172800, while the sum is 39.

The square root of 666442551 is about 25815.5486286850. The cubic root of 666442551 is about 873.4825622306.

The spelling of 666442551 in words is "six hundred sixty-six million, four hundred forty-two thousand, five hundred fifty-one".