645235740 has 96 divisors (see below), whose sum is σ = 2050191360. Its totient is φ = 168395328.

The previous prime is 645235733. The next prime is 645235753. The reversal of 645235740 is 47532546.

645235740 is a `hidden beast` number, since 64 + 5 + 23 + 574 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 645235695 and 645235704.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 12669 + ... + 38091.

It is an arithmetic number, because the mean of its divisors is an integer number (21356160).

Almost surely, 2^645235740 is an apocalyptic number.

645235740 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645235740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1025095680).

645235740 is an abundant number, since it is smaller than the sum of its proper divisors (1404955620).

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

645235740 is a wasteful number, since it uses less digits than its factorization.

645235740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25488 (or 25480 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 36.

The square root of 645235740 is about 25401.4909011263. The cubic root of 645235740 is about 864.1175090945.

The spelling of 645235740 in words is "six hundred forty-five million, two hundred thirty-five thousand, seven hundred forty".