1391866739 has 2 divisors, whose sum is σ = 1391866740. Its totient is φ = 1391866738.

The previous prime is 1391866727. The next prime is 1391866771. The reversal of 1391866739 is 9376681931.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1391866739 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1391866709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 695933369 + 695933370.

It is an arithmetic number, because the mean of its divisors is an integer number (695933370).

Almost surely, 2^1391866739 is an apocalyptic number.

1391866739 is a deficient number, since it is larger than the sum of its proper divisors (1).

1391866739 is an equidigital number, since it uses as much as digits as its factorization.

1391866739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1469664, while the sum is 53.

The square root of 1391866739 is about 37307.7302847547. The cubic root of 1391866739 is about 1116.5184026613.

The spelling of 1391866739 in words is "one billion, three hundred ninety-one million, eight hundred sixty-six thousand, seven hundred thirty-nine".