21231223442 has 16 divisors (see below), whose sum is σ = 37414464192. Its totient is φ = 8908205520.

The previous prime is 21231223417. The next prime is 21231223463. The reversal of 21231223442 is 24432213212.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37117238 + ... + 37117809.

It is an arithmetic number, because the mean of its divisors is an integer number (2338404012).

Almost surely, 2^21231223442 is an apocalyptic number.

21231223442 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21231223442 is a deficient number, since it is larger than the sum of its proper divisors (16183240750).

21231223442 is a wasteful number, since it uses less digits than its factorization.

21231223442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74235073.

The product of its digits is 4608, while the sum is 26.

Adding to 21231223442 its reverse (24432213212), we get a palindrome (45663436654).

The spelling of 21231223442 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty-three thousand, four hundred forty-two".