666540025 has 6 divisors (see below), whose sum is σ = 826509662. Its totient is φ = 533232000.

The previous prime is 666540019. The next prime is 666540067. The reversal of 666540025 is 520045666.

It can be written as a sum of positive squares in 3 ways, for example, as 39388176 + 627151849 = 6276^2 + 25043^2 .

It is a de Polignac number, because none of the positive numbers 2^k-666540025 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13330776 + ... + 13330825.

Almost surely, 2^666540025 is an apocalyptic number.

It is an amenable number.

666540025 is a deficient number, since it is larger than the sum of its proper divisors (159969637).

666540025 is a wasteful number, since it uses less digits than its factorization.

666540025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26661611 (or 26661606 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 666540025 is about 25817.4364529091. The cubic root of 666540025 is about 873.5251453903.

The spelling of 666540025 in words is "six hundred sixty-six million, five hundred forty thousand, twenty-five".