1391865421 has 2 divisors, whose sum is σ = 1391865422. Its totient is φ = 1391865420.

The previous prime is 1391865413. The next prime is 1391865443. The reversal of 1391865421 is 1245681931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 991305225 + 400560196 = 31485^2 + 20014^2 .

It is a cyclic number.

It is not a de Polignac number, because 1391865421 - 2³ = 1391865413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1391865481) 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, 695932710 + 695932711.

It is an arithmetic number, because the mean of its divisors is an integer number (695932711).

Almost surely, 2^1391865421 is an apocalyptic number.

It is an amenable number.

1391865421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1391865421 is an equidigital number, since it uses as much as digits as its factorization.

1391865421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 40.

The square root of 1391865421 is about 37307.7126208509. The cubic root of 1391865421 is about 1116.5180502397.

The spelling of 1391865421 in words is "one billion, three hundred ninety-one million, eight hundred sixty-five thousand, four hundred twenty-one".