645261642 has 48 divisors (see below), whose sum is σ = 1483634880. Its totient is φ = 202240896.

The previous prime is 645261613. The next prime is 645261647. The reversal of 645261642 is 246162546.

645261642 is a `hidden beast` number, since 6 + 4 + 5 + 2 + 6 + 1 + 642 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 645261597 and 645261606.

It is not an unprimeable number, because it can be changed into a prime (645261647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11218 + ... + 37634.

It is an arithmetic number, because the mean of its divisors is an integer number (30909060).

Almost surely, 2^645261642 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645261642, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (741817440).

645261642 is an abundant number, since it is smaller than the sum of its proper divisors (838373238).

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

645261642 is a wasteful number, since it uses less digits than its factorization.

645261642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26507 (or 26504 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 645261642 is about 25402.0007479726. Note that the first 3 decimals coincide. The cubic root of 645261642 is about 864.1290718309.

The spelling of 645261642 in words is "six hundred forty-five million, two hundred sixty-one thousand, six hundred forty-two".