15881381 has 2 divisors, whose sum is σ = 15881382. Its totient is φ = 15881380.

The previous prime is 15881377. The next prime is 15881389. The reversal of 15881381 is 18318851.

15881381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15880225 + 1156 = 3985^2 + 34^2 .

It is a cyclic number.

It is not a de Polignac number, because 15881381 - 2² = 15881377 is a prime.

It is a super-2 number, since 2×15881381² = 504436524934322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15881389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7940690 + 7940691.

It is an arithmetic number, because the mean of its divisors is an integer number (7940691).

Almost surely, 2^15881381 is an apocalyptic number.

It is an amenable number.

15881381 is a deficient number, since it is larger than the sum of its proper divisors (1).

15881381 is an equidigital number, since it uses as much as digits as its factorization.

15881381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 35.

The square root of 15881381 is about 3985.1450412752. The cubic root of 15881381 is about 251.3599540192.

The spelling of 15881381 in words is "fifteen million, eight hundred eighty-one thousand, three hundred eighty-one".