645453881 has 2 divisors, whose sum is σ = 645453882. Its totient is φ = 645453880.

The previous prime is 645453877. The next prime is 645453901. The reversal of 645453881 is 188354546.

645453881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 379470400 + 265983481 = 19480^2 + 16309^2 .

It is a cyclic number.

It is not a de Polignac number, because 645453881 - 2² = 645453877 is a prime.

It is a super-2 number, since 2×645453881² = 833221424995924322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (645453481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322726940 + 322726941.

It is an arithmetic number, because the mean of its divisors is an integer number (322726941).

Almost surely, 2^645453881 is an apocalyptic number.

It is an amenable number.

645453881 is a deficient number, since it is larger than the sum of its proper divisors (1).

645453881 is an equidigital number, since it uses as much as digits as its factorization.

645453881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 460800, while the sum is 44.

The square root of 645453881 is about 25405.7844004077. The cubic root of 645453881 is about 864.2148782715.

The spelling of 645453881 in words is "six hundred forty-five million, four hundred fifty-three thousand, eight hundred eighty-one".