188400640 has 88 divisors (see below), whose sum is σ = 466912512. Its totient is φ = 72867840.

The previous prime is 188400623. The next prime is 188400649. The reversal of 188400640 is 46004881.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (188400649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158127 + ... + 159313.

It is an arithmetic number, because the mean of its divisors is an integer number (5305824).

Almost surely, 2^188400640 is an apocalyptic number.

188400640 is a gapful number since it is divisible by the number (10) 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 188400640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (233456256).

188400640 is an abundant number, since it is smaller than the sum of its proper divisors (278511872).

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

188400640 is a wasteful number, since it uses less digits than its factorization.

188400640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243 (or 1225 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 31.

The square root of 188400640 is about 13725.9112630091. The cubic root of 188400640 is about 573.2720804702.

The spelling of 188400640 in words is "one hundred eighty-eight million, four hundred thousand, six hundred forty".