6399540 has 96 divisors (see below), whose sum is σ = 22767360. Its totient is φ = 1461888.

The previous prime is 6399527. The next prime is 6399541. The reversal of 6399540 is 459936.

It is a super-2 number, since 2×6399540² = 81908224423200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 6399495 and 6399504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6399541) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2934 + ... + 4626.

It is an arithmetic number, because the mean of its divisors is an integer number (237160).

Almost surely, 2^6399540 is an apocalyptic number.

6399540 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 6399540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11383680).

6399540 is an abundant number, since it is smaller than the sum of its proper divisors (16367820).

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

6399540 is a wasteful number, since it uses less digits than its factorization.

6399540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1718 (or 1710 counting only the distinct ones).

The product of its (nonzero) digits is 29160, while the sum is 36.

The square root of 6399540 is about 2529.7312110183. The cubic root of 6399540 is about 185.6591050486.

The spelling of 6399540 in words is "six million, three hundred ninety-nine thousand, five hundred forty".