21022120424 has 8 divisors (see below), whose sum is σ = 39416475810. Its totient is φ = 10511060208.

The previous prime is 21022120417. The next prime is 21022120439. The reversal of 21022120424 is 42402122012.

It can be written as a sum of positive squares in only one way, i.e., 16507624324 + 4514496100 = 128482^2 + 67190^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21022120396 and 21022120405.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1313882519 + ... + 1313882534.

Almost surely, 2^21022120424 is an apocalyptic number.

It is an amenable number.

21022120424 is a deficient number, since it is larger than the sum of its proper divisors (18394355386).

21022120424 is a wasteful number, since it uses less digits than its factorization.

21022120424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2627765059 (or 2627765055 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21022120424 its reverse (42402122012), we get a palindrome (63424242436).

The spelling of 21022120424 in words is "twenty-one billion, twenty-two million, one hundred twenty thousand, four hundred twenty-four".