221777920 has 312 divisors, whose sum is σ = 705933144. Its totient is φ = 66060288.

The previous prime is 221777887. The next prime is 221777951. The reversal of 221777920 is 29777122.

It can be written as a sum of positive squares in 4 ways, for example, as 16257024 + 205520896 = 4032^2 + 14336^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 221777920.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13045752 + ... + 13045768.

Almost surely, 2^221777920 is an apocalyptic number.

221777920 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 221777920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (352966572).

221777920 is an abundant number, since it is smaller than the sum of its proper divisors (484155224).

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

221777920 is a wasteful number, since it uses less digits than its factorization.

221777920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 24696, while the sum is 37.

The square root of 221777920 is about 14892.2100441808. The cubic root of 221777920 is about 605.3029195886.

The spelling of 221777920 in words is "two hundred twenty-one million, seven hundred seventy-seven thousand, nine hundred twenty".