221397380 has 24 divisors (see below), whose sum is σ = 465513048. Its totient is φ = 88448768.

The previous prime is 221397349. The next prime is 221397389. The reversal of 221397380 is 83793122.

221397380 = 16² + 17² + ... + 872².

It can be written as a sum of positive squares in 4 ways, for example, as 70795396 + 150601984 = 8414^2 + 12272^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 221397380.

It is not an unprimeable number, because it can be changed into a prime (221397389) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10682 + ... + 23598.

It is an arithmetic number, because the mean of its divisors is an integer number (19396377).

Almost surely, 2^221397380 is an apocalyptic number.

221397380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221397380 is an abundant number, since it is smaller than the sum of its proper divisors (244115668).

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

221397380 is a wasteful number, since it uses less digits than its factorization.

221397380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13783 (or 13781 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 221397380 is about 14879.4280804069. The cubic root of 221397380 is about 604.9565162382.

The spelling of 221397380 in words is "two hundred twenty-one million, three hundred ninety-seven thousand, three hundred eighty".