221211900 has 432 divisors, whose sum is σ = 888457024. Its totient is φ = 44789760.

The previous prime is 221211899. The next prime is 221211943. The reversal of 221211900 is 9112122.

It is a super-2 number, since 2×221211900² = 97869409403220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 3030264 + ... + 3030336.

Almost surely, 2^221211900 is an apocalyptic number.

221211900 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 221211900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (444228512).

221211900 is an abundant number, since it is smaller than the sum of its proper divisors (667245124).

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

221211900 is a wasteful number, since it uses less digits than its factorization.

221211900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 221211900 is about 14873.1940080132. The cubic root of 221211900 is about 604.7875309746.

It can be divided in two parts, 221211 and 900, that added together give a triangular number (222111 = T₆₆₆).

The spelling of 221211900 in words is "two hundred twenty-one million, two hundred eleven thousand, nine hundred".