13978621 has 2 divisors, whose sum is σ = 13978622. Its totient is φ = 13978620.

The previous prime is 13978619. The next prime is 13978633. The reversal of 13978621 is 12687931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7778521 + 6200100 = 2789^2 + 2490^2 .

It is a cyclic number.

It is not a de Polignac number, because 13978621 - 2¹ = 13978619 is a prime.

Together with 13978619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13978681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6989310 + 6989311.

It is an arithmetic number, because the mean of its divisors is an integer number (6989311).

Almost surely, 2^13978621 is an apocalyptic number.

It is an amenable number.

13978621 is a deficient number, since it is larger than the sum of its proper divisors (1).

13978621 is an equidigital number, since it uses as much as digits as its factorization.

13978621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 13978621 is about 3738.7994062265. The cubic root of 13978621 is about 240.8914819368.

The spelling of 13978621 in words is "thirteen million, nine hundred seventy-eight thousand, six hundred twenty-one".