221538438 has 48 divisors (see below), whose sum is σ = 546414336. Its totient is φ = 64212720.

The previous prime is 221538413. The next prime is 221538439. The reversal of 221538438 is 834835122.

221538438 is a `hidden beast` number, since 2 + 215 + 3 + 8 + 438 = 666.

It is a super-2 number, since 2×221538438² = 98158559022959688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221538439) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19770 + ... + 28877.

It is an arithmetic number, because the mean of its divisors is an integer number (11383632).

Almost surely, 2^221538438 is an apocalyptic number.

221538438 is an abundant number, since it is smaller than the sum of its proper divisors (324875898).

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

221538438 is a wasteful number, since it uses less digits than its factorization.

221538438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48689 (or 48686 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 221538438 is about 14884.1673599836. The cubic root of 221538438 is about 605.0849667794.

The spelling of 221538438 in words is "two hundred twenty-one million, five hundred thirty-eight thousand, four hundred thirty-eight".