669992621 has 2 divisors, whose sum is σ = 669992622. Its totient is φ = 669992620.

The previous prime is 669992551. The next prime is 669992629. The reversal of 669992621 is 126299966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 543542596 + 126450025 = 23314^2 + 11245^2 .

It is a cyclic number.

It is not a de Polignac number, because 669992621 - 2²² = 665798317 is a prime.

It is a super-2 number, since 2×669992621² = 897780224388899282, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p_34777958 and since 669992621 and 34777958 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 669992621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (669992629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334996310 + 334996311.

It is an arithmetic number, because the mean of its divisors is an integer number (334996311).

Almost surely, 2^669992621 is an apocalyptic number.

It is an amenable number.

669992621 is a deficient number, since it is larger than the sum of its proper divisors (1).

669992621 is an equidigital number, since it uses as much as digits as its factorization.

669992621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 629856, while the sum is 50.

The square root of 669992621 is about 25884.2156728768. The cubic root of 669992621 is about 875.0307998954.

The spelling of 669992621 in words is "six hundred sixty-nine million, nine hundred ninety-two thousand, six hundred twenty-one".