19881457 has 2 divisors, whose sum is σ = 19881458. Its totient is φ = 19881456.

The previous prime is 19881451. The next prime is 19881461. The reversal of 19881457 is 75418891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19368801 + 512656 = 4401^2 + 716^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19881457 is a prime.

It is not a weakly prime, because it can be changed into another prime (19881451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9940728 + 9940729.

It is an arithmetic number, because the mean of its divisors is an integer number (9940729).

Almost surely, 2^19881457 is an apocalyptic number.

It is an amenable number.

19881457 is a deficient number, since it is larger than the sum of its proper divisors (1).

19881457 is an equidigital number, since it uses as much as digits as its factorization.

19881457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 43.

The square root of 19881457 is about 4458.8627473830. The cubic root of 19881457 is about 270.9044065830.

The spelling of 19881457 in words is "nineteen million, eight hundred eighty-one thousand, four hundred fifty-seven".