381491521 has 2 divisors, whose sum is σ = 381491522. Its totient is φ = 381491520.

The previous prime is 381491507. The next prime is 381491563. The reversal of 381491521 is 125194183.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 244484496 + 137007025 = 15636^2 + 11705^2 .

It is an emirp because it is prime and its reverse (125194183) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 381491521 - 2⁷ = 381491393 is a prime.

It is not a weakly prime, because it can be changed into another prime (381491021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 190745760 + 190745761.

It is an arithmetic number, because the mean of its divisors is an integer number (190745761).

Almost surely, 2^381491521 is an apocalyptic number.

It is an amenable number.

381491521 is a deficient number, since it is larger than the sum of its proper divisors (1).

381491521 is an equidigital number, since it uses as much as digits as its factorization.

381491521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 34.

The square root of 381491521 is about 19531.8079296311. The cubic root of 381491521 is about 725.2620668126.

The spelling of 381491521 in words is "three hundred eighty-one million, four hundred ninety-one thousand, five hundred twenty-one".