397181621 has 2 divisors, whose sum is σ = 397181622. Its totient is φ = 397181620.

The previous prime is 397181599. The next prime is 397181639. The reversal of 397181621 is 126181793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204804721 + 192376900 = 14311^2 + 13870^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-397181621 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 (397181321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198590810 + 198590811.

It is an arithmetic number, because the mean of its divisors is an integer number (198590811).

Almost surely, 2^397181621 is an apocalyptic number.

It is an amenable number.

397181621 is a deficient number, since it is larger than the sum of its proper divisors (1).

397181621 is an equidigital number, since it uses as much as digits as its factorization.

397181621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 38.

The square root of 397181621 is about 19929.4159723761. The cubic root of 397181621 is about 735.0717199054.

It can be divided in two parts, 39718 and 1621, that multiplied together give a triangular number (64382878 = T₁₁₃₄₇).

The spelling of 397181621 in words is "three hundred ninety-seven million, one hundred eighty-one thousand, six hundred twenty-one".