397650991 has 2 divisors, whose sum is σ = 397650992. Its totient is φ = 397650990.

The previous prime is 397650983. The next prime is 397651123. The reversal of 397650991 is 199056793.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 397650991 - 2³ = 397650983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (397650191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198825495 + 198825496.

It is an arithmetic number, because the mean of its divisors is an integer number (198825496).

Almost surely, 2^397650991 is an apocalyptic number.

397650991 is a deficient number, since it is larger than the sum of its proper divisors (1).

397650991 is an equidigital number, since it uses as much as digits as its factorization.

397650991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 459270, while the sum is 49.

The square root of 397650991 is about 19941.1883046121. The cubic root of 397650991 is about 735.3611633024.

The spelling of 397650991 in words is "three hundred ninety-seven million, six hundred fifty thousand, nine hundred ninety-one".