21115223031 has 128 divisors (see below), whose sum is σ = 36391680000. Its totient is φ = 10834102272.

The previous prime is 21115223027. The next prime is 21115223039. The reversal of 21115223031 is 13032251112.

It is not a de Polignac number, because 21115223031 - 2² = 21115223027 is a prime.

It is a super-2 number, since 2×21115223031² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21115222989 and 21115223007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115223039) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 54280585 + ... + 54280973.

It is an arithmetic number, because the mean of its divisors is an integer number (284310000).

Almost surely, 2^21115223031 is an apocalyptic number.

21115223031 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21115223031 is a deficient number, since it is larger than the sum of its proper divisors (15276456969).

21115223031 is a wasteful number, since it uses less digits than its factorization.

21115223031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 566 (or 552 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

Adding to 21115223031 its reverse (13032251112), we get a palindrome (34147474143).

The spelling of 21115223031 in words is "twenty-one billion, one hundred fifteen million, two hundred twenty-three thousand, thirty-one".