221977845 has 18 divisors (see below), whose sum is σ = 384934914. Its totient is φ = 118334880.

The previous prime is 221977843. The next prime is 221977849. The reversal of 221977845 is 548779122.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 51753636 + 170224209 = 7194^2 + 13047^2 .

It is not a de Polignac number, because 221977845 - 2¹ = 221977843 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 221977845.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221977843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 98835 + ... + 101055.

It is an arithmetic number, because the mean of its divisors is an integer number (21385273).

Almost surely, 2^221977845 is an apocalyptic number.

It is an amenable number.

221977845 is a deficient number, since it is larger than the sum of its proper divisors (162957069).

221977845 is an frugal number, since it uses more digits than its factorization.

221977845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4453 (or 2229 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 221977845 is about 14898.9209340811. The cubic root of 221977845 is about 605.4847513970.

Multiplying 221977845 by its sum of digits (45), we get a square (9989003025 = 99945²).

221977845 divided by its sum of digits (45) gives a square (4932841 = 2221²).

The spelling of 221977845 in words is "two hundred twenty-one million, nine hundred seventy-seven thousand, eight hundred forty-five".