645881377 has 8 divisors (see below), whose sum is σ = 675581760. Its totient is φ = 616315920.

The previous prime is 645881333. The next prime is 645881381. The reversal of 645881377 is 773188546.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645881377 is a prime.

It is a super-2 number, since 2×645881377² = 834325506310832258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 645881377.

It is not an unprimeable number, because it can be changed into a prime (645881317) 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 in 7 ways as a sum of consecutive naturals, for example, 23874 + ... + 43147.

It is an arithmetic number, because the mean of its divisors is an integer number (84447720).

Almost surely, 2^645881377 is an apocalyptic number.

It is an amenable number.

645881377 is a deficient number, since it is larger than the sum of its proper divisors (29700383).

645881377 is a wasteful number, since it uses less digits than its factorization.

645881377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67463.

The product of its digits is 1128960, while the sum is 49.

The square root of 645881377 is about 25414.1963673849. The cubic root of 645881377 is about 864.4056313113.

The spelling of 645881377 in words is "six hundred forty-five million, eight hundred eighty-one thousand, three hundred seventy-seven".