646400440 has 32 divisors (see below), whose sum is σ = 1662173280. Its totient is φ = 221622912.

The previous prime is 646400429. The next prime is 646400477. The reversal of 646400440 is 44004646.

It is a super-3 number, since 3×646400440³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 646400399 and 646400408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1154007 + ... + 1154566.

It is an arithmetic number, because the mean of its divisors is an integer number (51942915).

Almost surely, 2^646400440 is an apocalyptic number.

It is an amenable number.

646400440 is an abundant number, since it is smaller than the sum of its proper divisors (1015772840).

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

646400440 is a wasteful number, since it uses less digits than its factorization.

646400440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2308591 (or 2308587 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 646400440 is about 25424.4063844173. The cubic root of 646400440 is about 864.6371293621.

The spelling of 646400440 in words is "six hundred forty-six million, four hundred thousand, four hundred forty".