381565621 has 2 divisors, whose sum is σ = 381565622. Its totient is φ = 381565620.

The previous prime is 381565549. The next prime is 381565627. The reversal of 381565621 is 126565183.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 222427396 + 159138225 = 14914^2 + 12615^2 .

It is a cyclic number.

It is not a de Polignac number, because 381565621 - 2¹⁷ = 381434549 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (381565627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 190782810 + 190782811.

It is an arithmetic number, because the mean of its divisors is an integer number (190782811).

Almost surely, 2^381565621 is an apocalyptic number.

It is an amenable number.

381565621 is a deficient number, since it is larger than the sum of its proper divisors (1).

381565621 is an equidigital number, since it uses as much as digits as its factorization.

381565621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43200, while the sum is 37.

The square root of 381565621 is about 19533.7047433404. The cubic root of 381565621 is about 725.3090214953.

The spelling of 381565621 in words is "three hundred eighty-one million, five hundred sixty-five thousand, six hundred twenty-one".