666521433 has 16 divisors (see below), whose sum is σ = 988262400. Its totient is φ = 443977200.

The previous prime is 666521423. The next prime is 666521437. The reversal of 666521433 is 334125666.

It is not a de Polignac number, because 666521433 - 2¹² = 666517337 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (666521437) 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, 24883 + ... + 44183.

It is an arithmetic number, because the mean of its divisors is an integer number (61766400).

Almost surely, 2^666521433 is an apocalyptic number.

It is an amenable number.

666521433 is a deficient number, since it is larger than the sum of its proper divisors (321740967).

666521433 is a wasteful number, since it uses less digits than its factorization.

666521433 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20589 (or 20583 counting only the distinct ones).

The product of its digits is 77760, while the sum is 36.

The square root of 666521433 is about 25817.0763836651. The cubic root of 666521433 is about 873.5170234822.

The spelling of 666521433 in words is "six hundred sixty-six million, five hundred twenty-one thousand, four hundred thirty-three".