397440221691 has 4 divisors (see below), whose sum is σ = 529920295592. Its totient is φ = 264960147792.

The previous prime is 397440221683. The next prime is 397440221713. The reversal of 397440221691 is 196122044793.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 397440221691 - 2³ = 397440221683 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 397440221691.

It is not an unprimeable number, because it can be changed into a prime (397440221611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66240036946 + ... + 66240036951.

It is an arithmetic number, because the mean of its divisors is an integer number (132480073898).

Almost surely, 2^397440221691 is an apocalyptic number.

397440221691 is a deficient number, since it is larger than the sum of its proper divisors (132480073901).

397440221691 is a wasteful number, since it uses less digits than its factorization.

397440221691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132480073900.

The product of its (nonzero) digits is 653184, while the sum is 48.

The spelling of 397440221691 in words is "three hundred ninety-seven billion, four hundred forty million, two hundred twenty-one thousand, six hundred ninety-one".