666251407 has 4 divisors (see below), whose sum is σ = 669932536. Its totient is φ = 662570280.

The previous prime is 666251401. The next prime is 666251431. The reversal of 666251407 is 704152666.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666251407 - 2¹¹ = 666249359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666251401) 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, 1840293 + ... + 1840654.

It is an arithmetic number, because the mean of its divisors is an integer number (167483134).

Almost surely, 2^666251407 is an apocalyptic number.

666251407 is a deficient number, since it is larger than the sum of its proper divisors (3681129).

666251407 is a wasteful number, since it uses less digits than its factorization.

666251407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3681128.

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 666251407 is about 25811.8462532226. The cubic root of 666251407 is about 873.3990456968.

The spelling of 666251407 in words is "six hundred sixty-six million, two hundred fifty-one thousand, four hundred seven".