1216681 has 2 divisors, whose sum is σ = 1216682. Its totient is φ = 1216680.

The previous prime is 1216619. The next prime is 1216693. The reversal of 1216681 is 1866121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 837225 + 379456 = 915^2 + 616^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216681 - 2¹⁵ = 1183913 is a prime.

It is a super-2 number, since 2×1216681² = 2960625311522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1216601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608340 + 608341.

It is an arithmetic number, because the mean of its divisors is an integer number (608341).

2^1216681 is an apocalyptic number.

It is an amenable number.

1216681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216681 is an equidigital number, since it uses as much as digits as its factorization.

1216681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 25.

The square root of 1216681 is about 1103.0326377764. The cubic root of 1216681 is about 106.7559874664.

The spelling of 1216681 in words is "one million, two hundred sixteen thousand, six hundred eighty-one".