661427983 has 2 divisors, whose sum is σ = 661427984. Its totient is φ = 661427982.

The previous prime is 661427957. The next prime is 661428011. The reversal of 661427983 is 389724166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661427983 - 2²¹ = 659330831 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661427903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330713991 + 330713992.

It is an arithmetic number, because the mean of its divisors is an integer number (330713992).

Almost surely, 2^661427983 is an apocalyptic number.

661427983 is a deficient number, since it is larger than the sum of its proper divisors (1).

661427983 is an equidigital number, since it uses as much as digits as its factorization.

661427983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 46.

The square root of 661427983 is about 25718.2422222048. The cubic root of 661427983 is about 871.2862389836.

The spelling of 661427983 in words is "six hundred sixty-one million, four hundred twenty-seven thousand, nine hundred eighty-three".