21021233440 has 24 divisors (see below), whose sum is σ = 49662664380. Its totient is φ = 8408493312.

The previous prime is 21021233437. The next prime is 21021233473. The reversal of 21021233440 is 4433212012.

It can be written as a sum of positive squares in 2 ways, for example, as 20866380304 + 154853136 = 144452^2 + 12444^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65691195 + ... + 65691514.

Almost surely, 2^21021233440 is an apocalyptic number.

21021233440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021233440 is an abundant number, since it is smaller than the sum of its proper divisors (28641430940).

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

21021233440 is a wasteful number, since it uses less digits than its factorization.

21021233440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131382724 (or 131382716 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

Adding to 21021233440 its reverse (4433212012), we get a palindrome (25454445452).

The spelling of 21021233440 in words is "twenty-one billion, twenty-one million, two hundred thirty-three thousand, four hundred forty".