1981457 has 2 divisors, whose sum is σ = 1981458. Its totient is φ = 1981456.

The previous prime is 1981429. The next prime is 1981471. The reversal of 1981457 is 7541891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1164241 + 817216 = 1079^2 + 904^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981457 - 2⁶ = 1981393 is a prime.

It is a super-3 number, since 3×1981457³ = 23338622043648152979, which contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1981417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990728 + 990729.

It is an arithmetic number, because the mean of its divisors is an integer number (990729).

2^1981457 is an apocalyptic number.

It is an amenable number.

1981457 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981457 is an equidigital number, since it uses as much as digits as its factorization.

1981457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 35.

The square root of 1981457 is about 1407.6423551457. The cubic root of 1981457 is about 125.6015167775.

The spelling of 1981457 in words is "one million, nine hundred eighty-one thousand, four hundred fifty-seven".