1615981 has 2 divisors, whose sum is σ = 1615982. Its totient is φ = 1615980.

The previous prime is 1615963. The next prime is 1615987. The reversal of 1615981 is 1895161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1602756 + 13225 = 1266^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 1615981 - 2⁵ = 1615949 is a prime.

It is a super-2 number, since 2×1615981² = 5222789184722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1615987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 807990 + 807991.

It is an arithmetic number, because the mean of its divisors is an integer number (807991).

2^1615981 is an apocalyptic number.

It is an amenable number.

1615981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1615981 is an equidigital number, since it uses as much as digits as its factorization.

1615981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 31.

The square root of 1615981 is about 1271.2124134070. The cubic root of 1615981 is about 117.3488262585.

The spelling of 1615981 in words is "one million, six hundred fifteen thousand, nine hundred eighty-one".