645661797 has 16 divisors (see below), whose sum is σ = 939578880. Its totient is φ = 391129200.

The previous prime is 645661789. The next prime is 645661801. The reversal of 645661797 is 797166546.

It is a happy number.

It is not a de Polignac number, because 645661797 - 2³ = 645661789 is a prime.

It is a super-2 number, since 2×645661797² = 833758312210538418, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645661697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115104 + ... + 120582.

It is an arithmetic number, because the mean of its divisors is an integer number (58723680).

Almost surely, 2^645661797 is an apocalyptic number.

It is an amenable number.

645661797 is a deficient number, since it is larger than the sum of its proper divisors (293917083).

645661797 is a wasteful number, since it uses less digits than its factorization.

645661797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9064.

The product of its digits is 1905120, while the sum is 51.

The square root of 645661797 is about 25409.8759737233. The cubic root of 645661797 is about 864.3076630110.

The spelling of 645661797 in words is "six hundred forty-five million, six hundred sixty-one thousand, seven hundred ninety-seven".