6397217721 has 12 divisors (see below), whose sum is σ = 9397043760. Its totient is φ = 4192526520.

The previous prime is 6397217707. The next prime is 6397217767. The reversal of 6397217721 is 1277127936.

6397217721 is a `hidden beast` number, since 639 + 7 + 2 + 1 + 7 + 7 + 2 + 1 = 666.

It is not a de Polignac number, because 6397217721 - 2¹⁰ = 6397216697 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (6397217621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6023215 + ... + 6024276.

It is an arithmetic number, because the mean of its divisors is an integer number (783086980).

Almost surely, 2^6397217721 is an apocalyptic number.

It is an amenable number.

6397217721 is a deficient number, since it is larger than the sum of its proper divisors (2999826039).

6397217721 is a wasteful number, since it uses less digits than its factorization.

6397217721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12047556 (or 12047553 counting only the distinct ones).

The product of its digits is 222264, while the sum is 45.

The square root of 6397217721 is about 79982.6088659278. The cubic root of 6397217721 is about 1856.3664487161.

The spelling of 6397217721 in words is "six billion, three hundred ninety-seven million, two hundred seventeen thousand, seven hundred twenty-one".