21112121987 has 12 divisors (see below), whose sum is σ = 23388626688. Its totient is φ = 19041699600.

The previous prime is 21112121977. The next prime is 21112121999. The reversal of 21112121987 is 78912121112.

It is not a de Polignac number, because 21112121987 - 2⁴ = 21112121971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112121977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 671564 + ... + 702297.

It is an arithmetic number, because the mean of its divisors is an integer number (1949052224).

Almost surely, 2^21112121987 is an apocalyptic number.

21112121987 is a deficient number, since it is larger than the sum of its proper divisors (2276504701).

21112121987 is a wasteful number, since it uses less digits than its factorization.

21112121987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1374010 (or 1373999 counting only the distinct ones).

The product of its digits is 4032, while the sum is 35.

The spelling of 21112121987 in words is "twenty-one billion, one hundred twelve million, one hundred twenty-one thousand, nine hundred eighty-seven".