221371956 has 144 divisors (see below), whose sum is σ = 629254080. Its totient is φ = 65180160.

The previous prime is 221371951. The next prime is 221371957. The reversal of 221371956 is 659173122.

221371956 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a self number, because there is not a number n which added to its sum of digits gives 221371956.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221371951) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1592535 + ... + 1592673.

It is an arithmetic number, because the mean of its divisors is an integer number (4369820).

Almost surely, 2^221371956 is an apocalyptic number.

221371956 is a gapful number since it is divisible by the number (26) 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 221371956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (314627040).

221371956 is an abundant number, since it is smaller than the sum of its proper divisors (407882124).

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

221371956 is a wasteful number, since it uses less digits than its factorization.

221371956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286 (or 281 counting only the distinct ones).

The product of its digits is 22680, while the sum is 36.

The square root of 221371956 is about 14878.5737219668. The cubic root of 221371956 is about 604.9333587777.

The spelling of 221371956 in words is "two hundred twenty-one million, three hundred seventy-one thousand, nine hundred fifty-six".