21123031884 has 24 divisors (see below), whose sum is σ = 49300930560. Its totient is φ = 7039031184.

The previous prime is 21123031883. The next prime is 21123031903. The reversal of 21123031884 is 48813032112.

It is not an unprimeable number, because it can be changed into a prime (21123031883) 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, 202644 + ... + 288635.

It is an arithmetic number, because the mean of its divisors is an integer number (2054205440).

Almost surely, 2^21123031884 is an apocalyptic number.

It is an amenable number.

21123031884 is an abundant number, since it is smaller than the sum of its proper divisors (28177898676).

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

21123031884 is a wasteful number, since it uses less digits than its factorization.

21123031884 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494869 (or 494867 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

Adding to 21123031884 its reverse (48813032112), we get a palindrome (69936063996).

The spelling of 21123031884 in words is "twenty-one billion, one hundred twenty-three million, thirty-one thousand, eight hundred eighty-four".