13870921 has 2 divisors, whose sum is σ = 13870922. Its totient is φ = 13870920.

The previous prime is 13870891. The next prime is 13870933. The reversal of 13870921 is 12907831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13801225 + 69696 = 3715^2 + 264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13870921 is a prime.

It is not a weakly prime, because it can be changed into another prime (13870951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6935460 + 6935461.

It is an arithmetic number, because the mean of its divisors is an integer number (6935461).

Almost surely, 2^13870921 is an apocalyptic number.

It is an amenable number.

13870921 is a deficient number, since it is larger than the sum of its proper divisors (1).

13870921 is an equidigital number, since it uses as much as digits as its factorization.

13870921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 13870921 is about 3724.3685370812. The cubic root of 13870921 is about 240.2712269325.

The spelling of 13870921 in words is "thirteen million, eight hundred seventy thousand, nine hundred twenty-one".