139556821 has 2 divisors, whose sum is σ = 139556822. Its totient is φ = 139556820.

The previous prime is 139556741. The next prime is 139556849. The reversal of 139556821 is 128655931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 136632721 + 2924100 = 11689^2 + 1710^2 .

It is a cyclic number.

It is not a de Polignac number, because 139556821 - 2⁷ = 139556693 is a prime.

It is a super-2 number, since 2×139556821² = 38952212575252082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139556861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69778410 + 69778411.

It is an arithmetic number, because the mean of its divisors is an integer number (69778411).

Almost surely, 2^139556821 is an apocalyptic number.

It is an amenable number.

139556821 is a deficient number, since it is larger than the sum of its proper divisors (1).

139556821 is an equidigital number, since it uses as much as digits as its factorization.

139556821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64800, while the sum is 40.

The square root of 139556821 is about 11813.4169908626. The cubic root of 139556821 is about 518.7009252264.

The spelling of 139556821 in words is "one hundred thirty-nine million, five hundred fifty-six thousand, eight hundred twenty-one".