666514621 has 2 divisors, whose sum is σ = 666514622. Its totient is φ = 666514620.

The previous prime is 666514619. The next prime is 666514637. The reversal of 666514621 is 126415666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 508006521 + 158508100 = 22539^2 + 12590^2 .

It is a cyclic number.

It is not a de Polignac number, because 666514621 - 2¹ = 666514619 is a prime.

Together with 666514619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666514721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333257310 + 333257311.

It is an arithmetic number, because the mean of its divisors is an integer number (333257311).

Almost surely, 2^666514621 is an apocalyptic number.

It is an amenable number.

666514621 is a deficient number, since it is larger than the sum of its proper divisors (1).

666514621 is an equidigital number, since it uses as much as digits as its factorization.

666514621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 37.

The square root of 666514621 is about 25816.9444551442. The cubic root of 666514621 is about 873.5140476248.

The spelling of 666514621 in words is "six hundred sixty-six million, five hundred fourteen thousand, six hundred twenty-one".