6401556 has 108 divisors (see below), whose sum is σ = 19918080. Its totient is φ = 1723680.

The previous prime is 6401543. The next prime is 6401557. The reversal of 6401556 is 6551046.

It is a happy number.

6401556 is a `hidden beast` number, since 640 + 15 + 5 + 6 = 666.

It is a super-2 number, since 2×6401556² = 81959838442272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6401557) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 33421 + ... + 33611.

Almost surely, 2^6401556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6401556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9959040).

6401556 is an abundant number, since it is smaller than the sum of its proper divisors (13516524).

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

6401556 is a wasteful number, since it uses less digits than its factorization.

6401556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 222 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 6401556 is about 2530.1296409473. The cubic root of 6401556 is about 185.6785986091.

The spelling of 6401556 in words is "six million, four hundred one thousand, five hundred fifty-six".