397880921 has 2 divisors, whose sum is σ = 397880922. Its totient is φ = 397880920.

The previous prime is 397880839. The next prime is 397880941. The reversal of 397880921 is 129088793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 200618896 + 197262025 = 14164^2 + 14045^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-397880921 is a prime.

It is not a weakly prime, because it can be changed into another prime (397880941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198940460 + 198940461.

It is an arithmetic number, because the mean of its divisors is an integer number (198940461).

Almost surely, 2^397880921 is an apocalyptic number.

It is an amenable number.

397880921 is a deficient number, since it is larger than the sum of its proper divisors (1).

397880921 is an equidigital number, since it uses as much as digits as its factorization.

397880921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 47.

The square root of 397880921 is about 19946.9526745315. The cubic root of 397880921 is about 735.5028696544.

The spelling of 397880921 in words is "three hundred ninety-seven million, eight hundred eighty thousand, nine hundred twenty-one".