666655551 has 6 divisors (see below), whose sum is σ = 962946920. Its totient is φ = 444437028.

The previous prime is 666655547. The next prime is 666655559. The reversal of 666655551 is 155556666.

It is not a de Polignac number, because 666655551 - 2² = 666655547 is a prime.

It is a super-2 number, since 2×666655551² = 888859247358227202, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 666655497 and 666655506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666655559) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 37036411 + ... + 37036428.

Almost surely, 2^666655551 is an apocalyptic number.

666655551 is a deficient number, since it is larger than the sum of its proper divisors (296291369).

666655551 is a wasteful number, since it uses less digits than its factorization.

666655551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74072845 (or 74072842 counting only the distinct ones).

The product of its digits is 810000, while the sum is 45.

The square root of 666655551 is about 25819.6737198594. The cubic root of 666655551 is about 873.5756094947.

The spelling of 666655551 in words is "six hundred sixty-six million, six hundred fifty-five thousand, five hundred fifty-one".