645857280 has 272 divisors, whose sum is σ = 2327820960. Its totient is φ = 169869312.

The previous prime is 645857269. The next prime is 645857293. The reversal of 645857280 is 82758546.

645857280 is a `hidden beast` number, since 64 + 585 + 7 + 2 + 8 + 0 = 666.

It is a super-2 number, since 2×645857280² = 834263252257996800, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8847324 + ... + 8847396.

Almost surely, 2^645857280 is an apocalyptic number.

645857280 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 645857280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1163910480).

645857280 is an abundant number, since it is smaller than the sum of its proper divisors (1681963680).

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

645857280 is an frugal number, since it uses more digits than its factorization.

645857280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 537600, while the sum is 45.

The square root of 645857280 is about 25413.7222775413. The cubic root of 645857280 is about 864.3948812250.

The spelling of 645857280 in words is "six hundred forty-five million, eight hundred fifty-seven thousand, two hundred eighty".