661974811 has 2 divisors, whose sum is σ = 661974812. Its totient is φ = 661974810.

The previous prime is 661974787. The next prime is 661974827. The reversal of 661974811 is 118479166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661974811 - 2⁵ = 661974779 is a prime.

It is not a weakly prime, because it can be changed into another prime (661974211) 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, 330987405 + 330987406.

It is an arithmetic number, because the mean of its divisors is an integer number (330987406).

Almost surely, 2^661974811 is an apocalyptic number.

661974811 is a deficient number, since it is larger than the sum of its proper divisors (1).

661974811 is an equidigital number, since it uses as much as digits as its factorization.

661974811 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 661974811 is about 25728.8711567375. The cubic root of 661974811 is about 871.5262814805.

The spelling of 661974811 in words is "six hundred sixty-one million, nine hundred seventy-four thousand, eight hundred eleven".