6446640 has 40 divisors (see below), whose sum is σ = 19985328. Its totient is φ = 1719040.

The previous prime is 6446633. The next prime is 6446651. The reversal of 6446640 is 466446.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 6446598 and 6446607.

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, 13191 + ... + 13670.

Almost surely, 2^6446640 is an apocalyptic number.

6446640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6446640 is an abundant number, since it is smaller than the sum of its proper divisors (13538688).

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

6446640 is a wasteful number, since it uses less digits than its factorization.

6446640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26877 (or 26871 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 6446640 is about 2539.0234343149. The cubic root of 6446640 is about 186.1134699007.

The spelling of 6446640 in words is "six million, four hundred forty-six thousand, six hundred forty".