21120111101988 has 54 divisors (see below), whose sum is σ = 55291357129554. Its totient is φ = 6797277126528.

The previous prime is 21120111101987. The next prime is 21120111102179. The reversal of 21120111101988 is 88910111102112.

It can be written as a sum of positive squares in 3 ways, for example, as 5573556062244 + 15546555039744 = 2360838^2 + 3942912^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21120111101981) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 348762681 + ... + 348823232.

Almost surely, 2^{21120111101988} is an apocalyptic number.

It is an amenable number.

21120111101988 is an abundant number, since it is smaller than the sum of its proper divisors (34171246027566).

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

21120111101988 is a wasteful number, since it uses less digits than its factorization.

21120111101988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697585981 (or 697585947 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 36.

The spelling of 21120111101988 in words is "twenty-one trillion, one hundred twenty billion, one hundred eleven million, one hundred one thousand, nine hundred eighty-eight".