15209981 has 2 divisors, whose sum is σ = 15209982. Its totient is φ = 15209980.

The previous prime is 15209963. The next prime is 15209989. The reversal of 15209981 is 18990251.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8213956 + 6996025 = 2866^2 + 2645^2 .

It is a cyclic number.

It is not a de Polignac number, because 15209981 - 2¹⁸ = 14947837 is a prime.

It is a super-2 number, since 2×15209981² = 462687044040722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15209989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7604990 + 7604991.

It is an arithmetic number, because the mean of its divisors is an integer number (7604991).

Almost surely, 2^15209981 is an apocalyptic number.

It is an amenable number.

15209981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15209981 is an equidigital number, since it uses as much as digits as its factorization.

15209981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 15209981 is about 3899.9975641018. The cubic root of 15209981 is about 247.7666737583.

The spelling of 15209981 in words is "fifteen million, two hundred nine thousand, nine hundred eighty-one".