645697140 has 288 divisors, whose sum is σ = 2173624320. Its totient is φ = 142560000.

The previous prime is 645697123. The next prime is 645697153. The reversal of 645697140 is 41796546.

645697140 = 478² + 479² + ... + 1269².

It is a junction number, because it is equal to n+sod(n) for n = 645697092 and 645697101.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4276065 + ... + 4276215.

Almost surely, 2^645697140 is an apocalyptic number.

645697140 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 645697140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1086812160).

645697140 is an abundant number, since it is smaller than the sum of its proper divisors (1527927180).

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

645697140 is a wasteful number, since it uses less digits than its factorization.

645697140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235 (or 222 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 42.

The square root of 645697140 is about 25410.5714221463. The cubic root of 645697140 is about 864.3234332220.

The spelling of 645697140 in words is "six hundred forty-five million, six hundred ninety-seven thousand, one hundred forty".