221819904 has 176 divisors, whose sum is σ = 672071040. Its totient is φ = 72253440.

The previous prime is 221819903. The next prime is 221819933. The reversal of 221819904 is 409918122.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221819903) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1962952 + ... + 1963064.

Almost surely, 2^221819904 is an apocalyptic number.

221819904 is a gapful number since it is divisible by the number (24) 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 221819904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (336035520).

221819904 is an abundant number, since it is smaller than the sum of its proper divisors (450251136).

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

221819904 is a wasteful number, since it uses less digits than its factorization.

221819904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213 (or 189 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 221819904 is about 14893.6195734952. The cubic root of 221819904 is about 605.3411131027.

It can be divided in two parts, 2218 and 19904, that added together give a palindrome (22122).

The spelling of 221819904 in words is "two hundred twenty-one million, eight hundred nineteen thousand, nine hundred four".