1239121661 has 2 divisors, whose sum is σ = 1239121662. Its totient is φ = 1239121660.

The previous prime is 1239121627. The next prime is 1239121673. The reversal of 1239121661 is 1661219321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1161787225 + 77334436 = 34085^2 + 8794^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1239121661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1239121861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 619560830 + 619560831.

It is an arithmetic number, because the mean of its divisors is an integer number (619560831).

Almost surely, 2^1239121661 is an apocalyptic number.

It is an amenable number.

1239121661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1239121661 is an equidigital number, since it uses as much as digits as its factorization.

1239121661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 1239121661 is about 35201.1599382748. The cubic root of 1239121661 is about 1074.0833465159.

The spelling of 1239121661 in words is "one billion, two hundred thirty-nine million, one hundred twenty-one thousand, six hundred sixty-one".