13731821 has 2 divisors, whose sum is σ = 13731822. Its totient is φ = 13731820.

The previous prime is 13731799. The next prime is 13731827. The reversal of 13731821 is 12813731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8940100 + 4791721 = 2990^2 + 2189^2 .

It is a cyclic number.

It is not a de Polignac number, because 13731821 - 2¹⁴ = 13715437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13731827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6865910 + 6865911.

It is an arithmetic number, because the mean of its divisors is an integer number (6865911).

Almost surely, 2^13731821 is an apocalyptic number.

It is an amenable number.

13731821 is a deficient number, since it is larger than the sum of its proper divisors (1).

13731821 is an equidigital number, since it uses as much as digits as its factorization.

13731821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 26.

The square root of 13731821 is about 3705.6471769449. The cubic root of 13731821 is about 239.4653666271.

The spelling of 13731821 in words is "thirteen million, seven hundred thirty-one thousand, eight hundred twenty-one".