645554961 has 32 divisors (see below), whose sum is σ = 999947520. Its totient is φ = 410838912.

The previous prime is 645554941. The next prime is 645554971. The reversal of 645554961 is 169455546.

645554961 is a `hidden beast` number, since 6 + 4 + 5 + 554 + 96 + 1 = 666.

It is not a de Polignac number, because 645554961 - 2⁵ = 645554929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645554941) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 531591 + ... + 532803.

It is an arithmetic number, because the mean of its divisors is an integer number (31248360).

Almost surely, 2^645554961 is an apocalyptic number.

It is an amenable number.

645554961 is a deficient number, since it is larger than the sum of its proper divisors (354392559).

645554961 is a wasteful number, since it uses less digits than its factorization.

645554961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2102 (or 2096 counting only the distinct ones).

The product of its digits is 648000, while the sum is 45.

The square root of 645554961 is about 25407.7736332800. The cubic root of 645554961 is about 864.2599887913.

It can be divided in two parts, 6455 and 54961, that added together give a palindrome (61416).

The spelling of 645554961 in words is "six hundred forty-five million, five hundred fifty-four thousand, nine hundred sixty-one".