661929139 has 2 divisors, whose sum is σ = 661929140. Its totient is φ = 661929138.

The previous prime is 661929131. The next prime is 661929161. The reversal of 661929139 is 931929166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661929139 - 2³ = 661929131 is a prime.

It is not a weakly prime, because it can be changed into another prime (661929131) 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, 330964569 + 330964570.

It is an arithmetic number, because the mean of its divisors is an integer number (330964570).

Almost surely, 2^661929139 is an apocalyptic number.

661929139 is a deficient number, since it is larger than the sum of its proper divisors (1).

661929139 is an equidigital number, since it uses as much as digits as its factorization.

661929139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 157464, while the sum is 46.

The square root of 661929139 is about 25727.9835781975. The cubic root of 661929139 is about 871.5062377854.

The spelling of 661929139 in words is "six hundred sixty-one million, nine hundred twenty-nine thousand, one hundred thirty-nine".