669006521 has 2 divisors, whose sum is σ = 669006522. Its totient is φ = 669006520.

The previous prime is 669006463. The next prime is 669006563. The reversal of 669006521 is 125600966.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 668946496 + 60025 = 25864^2 + 245^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-669006521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (669006421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334503260 + 334503261.

It is an arithmetic number, because the mean of its divisors is an integer number (334503261).

Almost surely, 2^669006521 is an apocalyptic number.

It is an amenable number.

669006521 is a deficient number, since it is larger than the sum of its proper divisors (1).

669006521 is an equidigital number, since it uses as much as digits as its factorization.

669006521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 669006521 is about 25865.1603706608. The cubic root of 669006521 is about 874.6012968849.

The spelling of 669006521 in words is "six hundred sixty-nine million, six thousand, five hundred twenty-one".