665470521 has 12 divisors (see below), whose sum is σ = 992243200. Its totient is φ = 429335640.

The previous prime is 665470501. The next prime is 665470529. The reversal of 665470521 is 125074566.

It is a happy number.

665470521 is a `hidden beast` number, since 6 + 65 + 4 + 70 + 521 = 666.

665470521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 665470521 - 2¹⁸ = 665208377 is a prime.

It is a super-2 number, since 2×665470521² = 885702028640022882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665470529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1192321 + ... + 1192878.

Almost surely, 2^665470521 is an apocalyptic number.

It is an amenable number.

665470521 is a deficient number, since it is larger than the sum of its proper divisors (326772679).

665470521 is a wasteful number, since it uses less digits than its factorization.

665470521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2385236 (or 2385233 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

The square root of 665470521 is about 25796.7153141635. The cubic root of 665470521 is about 873.0576872088.

The spelling of 665470521 in words is "six hundred sixty-five million, four hundred seventy thousand, five hundred twenty-one".