21131223240 has 64 divisors (see below), whose sum is σ = 63659001600. Its totient is φ = 5611407872.

The previous prime is 21131223209. The next prime is 21131223263. The reversal of 21131223240 is 4232213112.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 339717 + ... + 397076.

It is an arithmetic number, because the mean of its divisors is an integer number (994671900).

Almost surely, 2^21131223240 is an apocalyptic number.

21131223240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21131223240 is an abundant number, since it is smaller than the sum of its proper divisors (42527778360).

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

21131223240 is a wasteful number, since it uses less digits than its factorization.

21131223240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737046 (or 737042 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

Adding to 21131223240 its reverse (4232213112), we get a palindrome (25363436352).

The spelling of 21131223240 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-three thousand, two hundred forty".