221394636 has 18 divisors (see below), whose sum is σ = 559636532. Its totient is φ = 73798200.

The previous prime is 221394617. The next prime is 221394637. The reversal of 221394636 is 636493122.

221394636 is a `hidden beast` number, since 2 + 2 + 13 + 9 + 4 + 636 = 666.

221394636 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 6149851 = 221394636 / (2 + 2 + 1 + 3 + 9 + 4 + 6 + 3 + 6).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 221394636.

It is not an unprimeable number, because it can be changed into a prime (221394637) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3074890 + ... + 3074961.

Almost surely, 2^221394636 is an apocalyptic number.

It is an amenable number.

221394636 is an abundant number, since it is smaller than the sum of its proper divisors (338241896).

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

221394636 is a wasteful number, since it uses less digits than its factorization.

221394636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6149861 (or 6149856 counting only the distinct ones).

The product of its digits is 46656, while the sum is 36.

The square root of 221394636 is about 14879.3358722760. The cubic root of 221394636 is about 604.9540169500.

The spelling of 221394636 in words is "two hundred twenty-one million, three hundred ninety-four thousand, six hundred thirty-six".