661942579 has 2 divisors, whose sum is σ = 661942580. Its totient is φ = 661942578.

The previous prime is 661942571. The next prime is 661942601. The reversal of 661942579 is 975249166.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661942579 - 2³ = 661942571 is a prime.

It is not a weakly prime, because it can be changed into another prime (661942571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330971289 + 330971290.

It is an arithmetic number, because the mean of its divisors is an integer number (330971290).

Almost surely, 2^661942579 is an apocalyptic number.

661942579 is a deficient number, since it is larger than the sum of its proper divisors (1).

661942579 is an equidigital number, since it uses as much as digits as its factorization.

661942579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 49.

The square root of 661942579 is about 25728.2447710682. The cubic root of 661942579 is about 871.5121361834.

The spelling of 661942579 in words is "six hundred sixty-one million, nine hundred forty-two thousand, five hundred seventy-nine".