215638664400 has 240 divisors, whose sum is σ = 769041403200. Its totient is φ = 57389207040.

The previous prime is 215638664387. The next prime is 215638664401. The reversal of 215638664400 is 4466836512.

215638664400 is a `hidden beast` number, since 2 + 1 + 5 + 638 + 6 + 6 + 4 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215638664401) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5477587 + ... + 5516813.

It is an arithmetic number, because the mean of its divisors is an integer number (3204339180).

Almost surely, 2^215638664400 is an apocalyptic number.

215638664400 is a gapful number since it is divisible by the number (20) 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 215638664400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (384520701600).

215638664400 is an abundant number, since it is smaller than the sum of its proper divisors (553402738800).

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

215638664400 is a wasteful number, since it uses less digits than its factorization.

215638664400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39763 (or 39746 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 45.

The spelling of 215638664400 in words is "two hundred fifteen billion, six hundred thirty-eight million, six hundred sixty-four thousand, four hundred".