645682993 has 2 divisors, whose sum is σ = 645682994. Its totient is φ = 645682992.

The previous prime is 645682991. The next prime is 645683033. The reversal of 645682993 is 399286546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 638219169 + 7463824 = 25263^2 + 2732^2 .

It is a cyclic number.

It is not a de Polignac number, because 645682993 - 2¹ = 645682991 is a prime.

It is a super-3 number, since 3×645682993³ (a number of 27 digits) contains 333 as substring.

Together with 645682991, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 645682993.

It is not a weakly prime, because it can be changed into another prime (645682991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322841496 + 322841497.

It is an arithmetic number, because the mean of its divisors is an integer number (322841497).

Almost surely, 2^645682993 is an apocalyptic number.

It is an amenable number.

645682993 is a deficient number, since it is larger than the sum of its proper divisors (1).

645682993 is an equidigital number, since it uses as much as digits as its factorization.

645682993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2799360, while the sum is 52.

The square root of 645682993 is about 25410.2930522259. The cubic root of 645682993 is about 864.3171208339.

The spelling of 645682993 in words is "six hundred forty-five million, six hundred eighty-two thousand, nine hundred ninety-three".