13981921 has 2 divisors, whose sum is σ = 13981922. Its totient is φ = 13981920.

The previous prime is 13981901. The next prime is 13981927. The reversal of 13981921 is 12918931.

13981921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13242321 + 739600 = 3639^2 + 860^2 .

It is an emirp because it is prime and its reverse (12918931) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13981921 - 2¹⁵ = 13949153 is a prime.

It is a super-2 number, since 2×13981921² = 390988229700482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (13981927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6990960 + 6990961.

It is an arithmetic number, because the mean of its divisors is an integer number (6990961).

Almost surely, 2^13981921 is an apocalyptic number.

It is an amenable number.

13981921 is a deficient number, since it is larger than the sum of its proper divisors (1).

13981921 is an equidigital number, since it uses as much as digits as its factorization.

13981921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 34.

The square root of 13981921 is about 3739.2406983237. The cubic root of 13981921 is about 240.9104365805.

The spelling of 13981921 in words is "thirteen million, nine hundred eighty-one thousand, nine hundred twenty-one".