646997760 has 288 divisors, whose sum is σ = 2331631680. Its totient is φ = 169869312.

The previous prime is 646997749. The next prime is 646997773. The reversal of 646997760 is 67799646.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×646997760² = 837212202890035200, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 646997697 and 646997706.

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, 3352224 + ... + 3352416.

Almost surely, 2^646997760 is an apocalyptic number.

646997760 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 646997760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1165815840).

646997760 is an abundant number, since it is smaller than the sum of its proper divisors (1684633920).

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

646997760 is a wasteful number, since it uses less digits than its factorization.

646997760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 3429216, while the sum is 54.

The square root of 646997760 is about 25436.1506521722. The cubic root of 646997760 is about 864.9033761117.

The spelling of 646997760 in words is "six hundred forty-six million, nine hundred ninety-seven thousand, seven hundred sixty".