321640657 has 4 divisors (see below), whose sum is σ = 346382260. Its totient is φ = 296899056.

The previous prime is 321640643. The next prime is 321640681. The reversal of 321640657 is 756046123.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 55591936 + 266048721 = 7456^2 + 16311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-321640657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (321640157) 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, 12370782 + ... + 12370807.

It is an arithmetic number, because the mean of its divisors is an integer number (86595565).

Almost surely, 2^321640657 is an apocalyptic number.

It is an amenable number.

321640657 is a deficient number, since it is larger than the sum of its proper divisors (24741603).

321640657 is a wasteful number, since it uses less digits than its factorization.

321640657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24741602.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 321640657 is about 17934.3429486558. The cubic root of 321640657 is about 685.1573382520.

The spelling of 321640657 in words is "three hundred twenty-one million, six hundred forty thousand, six hundred fifty-seven".