19791257 has 2 divisors, whose sum is σ = 19791258. Its totient is φ = 19791256.

The previous prime is 19791251. The next prime is 19791269. The reversal of 19791257 is 75219791.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19545241 + 246016 = 4421^2 + 496^2 .

It is an emirp because it is prime and its reverse (75219791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19791257 - 2⁴ = 19791241 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19791251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9895628 + 9895629.

It is an arithmetic number, because the mean of its divisors is an integer number (9895629).

Almost surely, 2^19791257 is an apocalyptic number.

It is an amenable number.

19791257 is a deficient number, since it is larger than the sum of its proper divisors (1).

19791257 is an equidigital number, since it uses as much as digits as its factorization.

19791257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39690, while the sum is 41.

The square root of 19791257 is about 4448.7365622163. The cubic root of 19791257 is about 270.4940975407.

The spelling of 19791257 in words is "nineteen million, seven hundred ninety-one thousand, two hundred fifty-seven".