1639752661 has 2 divisors, whose sum is σ = 1639752662. Its totient is φ = 1639752660.

The previous prime is 1639752659. The next prime is 1639752679. The reversal of 1639752661 is 1662579361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1310874436 + 328878225 = 36206^2 + 18135^2 .

It is a cyclic number.

It is not a de Polignac number, because 1639752661 - 2¹ = 1639752659 is a prime.

Together with 1639752659, 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 (1639752601) 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, 819876330 + 819876331.

It is an arithmetic number, because the mean of its divisors is an integer number (819876331).

Almost surely, 2^1639752661 is an apocalyptic number.

It is an amenable number.

1639752661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1639752661 is an equidigital number, since it uses as much as digits as its factorization.

1639752661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 408240, while the sum is 46.

The square root of 1639752661 is about 40493.8595468498. The cubic root of 1639752661 is about 1179.2144203834.

The spelling of 1639752661 in words is "one billion, six hundred thirty-nine million, seven hundred fifty-two thousand, six hundred sixty-one".