21111312015 has 128 divisors (see below), whose sum is σ = 41350963200. Its totient is φ = 10178472960.

The previous prime is 21111311999. The next prime is 21111312043. The reversal of 21111312015 is 51021311112.

It is not a de Polignac number, because 21111312015 - 2⁴ = 21111311999 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 5802777 + ... + 5806413.

It is an arithmetic number, because the mean of its divisors is an integer number (323054400).

Almost surely, 2^21111312015 is an apocalyptic number.

21111312015 is a deficient number, since it is larger than the sum of its proper divisors (20239651185).

21111312015 is a wasteful number, since it uses less digits than its factorization.

21111312015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3774 (or 3768 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 18.

Adding to 21111312015 its reverse (51021311112), we get a palindrome (72132623127).

The spelling of 21111312015 in words is "twenty-one billion, one hundred eleven million, three hundred twelve thousand, fifteen".