645693390 has 64 divisors (see below), whose sum is σ = 1724788800. Its totient is φ = 171891072.

The previous prime is 645693361. The next prime is 645693403. The reversal of 645693390 is 93396546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 189744 + ... + 193116.

It is an arithmetic number, because the mean of its divisors is an integer number (26949825).

Almost surely, 2^645693390 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645693390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (862394400).

645693390 is an abundant number, since it is smaller than the sum of its proper divisors (1079095410).

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

645693390 is a wasteful number, since it uses less digits than its factorization.

645693390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4098 (or 4092 counting only the distinct ones).

The product of its (nonzero) digits is 524880, while the sum is 45.

The square root of 645693390 is about 25410.4976338520. The cubic root of 645693390 is about 864.3217599819.

The spelling of 645693390 in words is "six hundred forty-five million, six hundred ninety-three thousand, three hundred ninety".