643155997 has 16 divisors (see below), whose sum is σ = 726926400. Its totient is φ = 563664640.

The previous prime is 643155973. The next prime is 643156013. The reversal of 643155997 is 799551346.

It is a de Polignac number, because none of the positive numbers 2^k-643155997 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 643155997.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643155907) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 301029 + ... + 303157.

It is an arithmetic number, because the mean of its divisors is an integer number (45432900).

Almost surely, 2^643155997 is an apocalyptic number.

It is an amenable number.

643155997 is a deficient number, since it is larger than the sum of its proper divisors (83770403).

643155997 is a wasteful number, since it uses less digits than its factorization.

643155997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3116.

The product of its digits is 1020600, while the sum is 49.

The square root of 643155997 is about 25360.5204402433. The cubic root of 643155997 is about 863.1880933984.

The spelling of 643155997 in words is "six hundred forty-three million, one hundred fifty-five thousand, nine hundred ninety-seven".