645521701 has 8 divisors (see below), whose sum is σ = 728488800. Its totient is φ = 566601840.

The previous prime is 645521693. The next prime is 645521707. The reversal of 645521701 is 107125546.

645521701 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645521701 - 2³ = 645521693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645521707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1011471 + ... + 1012108.

It is an arithmetic number, because the mean of its divisors is an integer number (91061100).

Almost surely, 2^645521701 is an apocalyptic number.

It is an amenable number.

645521701 is a deficient number, since it is larger than the sum of its proper divisors (82967099).

645521701 is a wasteful number, since it uses less digits than its factorization.

645521701 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2023619.

The product of its (nonzero) digits is 8400, while the sum is 31.

The square root of 645521701 is about 25407.1191007560. The cubic root of 645521701 is about 864.2451458615.

The spelling of 645521701 in words is "six hundred forty-five million, five hundred twenty-one thousand, seven hundred one".