645657894 has 96 divisors (see below), whose sum is σ = 1685938176. Its totient is φ = 174674880.

The previous prime is 645657893. The next prime is 645657923. The reversal of 645657894 is 498756546.

645657894 is a `hidden beast` number, since 6 + 4 + 565 + 78 + 9 + 4 = 666.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 645657894.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645657893) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 181824 + ... + 185340.

It is an arithmetic number, because the mean of its divisors is an integer number (17561856).

Almost surely, 2^645657894 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645657894, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (842969088).

645657894 is an abundant number, since it is smaller than the sum of its proper divisors (1040280282).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645657894 is a wasteful number, since it uses less digits than its factorization.

645657894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3610 (or 3607 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The square root of 645657894 is about 25409.7991727601. The cubic root of 645657894 is about 864.3059214389.

The spelling of 645657894 in words is "six hundred forty-five million, six hundred fifty-seven thousand, eight hundred ninety-four".