221431540 has 24 divisors (see below), whose sum is σ = 507280032. Its totient is φ = 80520480.

The previous prime is 221431531. The next prime is 221431541. The reversal of 221431540 is 45134122.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221431541) 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, 503034 + ... + 503473.

It is an arithmetic number, because the mean of its divisors is an integer number (21136668).

Almost surely, 2^221431540 is an apocalyptic number.

221431540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221431540 is an abundant number, since it is smaller than the sum of its proper divisors (285848492).

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

221431540 is a wasteful number, since it uses less digits than its factorization.

221431540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1006527 (or 1006525 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 221431540 is about 14880.5759297145. The cubic root of 221431540 is about 604.9876280966.

Adding to 221431540 its reverse (45134122), we get a palindrome (266565662).

The spelling of 221431540 in words is "two hundred twenty-one million, four hundred thirty-one thousand, five hundred forty".