221801436 has 96 divisors (see below), whose sum is σ = 588922880. Its totient is φ = 72176832.

The previous prime is 221801387. The next prime is 221801453. The reversal of 221801436 is 634108122.

221801436 is a `hidden beast` number, since 221 + 8 + 0 + 1 + 436 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1412670 + ... + 1412826.

Almost surely, 2^221801436 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 221801436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (294461440).

221801436 is an abundant number, since it is smaller than the sum of its proper divisors (367121444).

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

221801436 is a wasteful number, since it uses less digits than its factorization.

221801436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400 (or 392 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 221801436 is about 14892.9995635533. Note that the first 3 decimals coincide. The cubic root of 221801436 is about 605.3243130625.

Adding to 221801436 its reverse (634108122), we get a palindrome (855909558).

The spelling of 221801436 in words is "two hundred twenty-one million, eight hundred one thousand, four hundred thirty-six".