645621616 has 10 divisors (see below), whose sum is σ = 1250891912. Its totient is φ = 322810800.

The previous prime is 645621583. The next prime is 645621617. The reversal of 645621616 is 616126546.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645621617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20175660 + ... + 20175691.

Almost surely, 2^645621616 is an apocalyptic number.

It is an amenable number.

645621616 is a deficient number, since it is larger than the sum of its proper divisors (605270296).

645621616 is a wasteful number, since it uses less digits than its factorization.

645621616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40351359 (or 40351353 counting only the distinct ones).

The product of its digits is 51840, while the sum is 37.

The square root of 645621616 is about 25409.0853042765. The cubic root of 645621616 is about 864.2897333628.

The spelling of 645621616 in words is "six hundred forty-five million, six hundred twenty-one thousand, six hundred sixteen".