645966397440 has 1632 divisors, whose sum is σ = 2885491365120. Its totient is φ = 130006646784.

The previous prime is 645966397429. The next prime is 645966397459. The reversal of 645966397440 is 44793669546.

645966397440 is a `hidden beast` number, since 6 + 4 + 596 + 6 + 39 + 7 + 4 + 4 + 0 = 666.

It is a super-2 number, since 2×645966397440² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

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, 7782727639 + ... + 7782727721.

Almost surely, 2^645966397440 is an apocalyptic number.

645966397440 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 645966397440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1442745682560).

645966397440 is an abundant number, since it is smaller than the sum of its proper divisors (2239524967680).

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

645966397440 is a wasteful number, since it uses less digits than its factorization.

645966397440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 117573120, while the sum is 63.

The spelling of 645966397440 in words is "six hundred forty-five billion, nine hundred sixty-six million, three hundred ninety-seven thousand, four hundred forty".