645992658 has 48 divisors (see below), whose sum is σ = 1454412960. Its totient is φ = 214897536.

The previous prime is 645992653. The next prime is 645992681. The reversal of 645992658 is 856299546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (645992653) 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, 319266 + ... + 321282.

It is an arithmetic number, because the mean of its divisors is an integer number (30300270).

Almost surely, 2^645992658 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645992658, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (727206480).

645992658 is an abundant number, since it is smaller than the sum of its proper divisors (808420302).

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

645992658 is a wasteful number, since it uses less digits than its factorization.

645992658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2693 (or 2681 counting only the distinct ones).

The product of its digits is 4665600, while the sum is 54.

The square root of 645992658 is about 25416.3856203041. The cubic root of 645992658 is about 864.4552722116.

The spelling of 645992658 in words is "six hundred forty-five million, nine hundred ninety-two thousand, six hundred fifty-eight".