21111010021987 has 4 divisors (see below), whose sum is σ = 21171500022400. Its totient is φ = 21050520021576.

The previous prime is 21111010021979. The next prime is 21111010021991. The reversal of 21111010021987 is 78912001011112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21111010021987 - 2³ = 21111010021979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111010021187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30244999683 + ... + 30245000380.

It is an arithmetic number, because the mean of its divisors is an integer number (5292875005600).

Almost surely, 2^{21111010021987} is an apocalyptic number.

21111010021987 is a deficient number, since it is larger than the sum of its proper divisors (60490000413).

21111010021987 is an equidigital number, since it uses as much as digits as its factorization.

21111010021987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60490000412.

The product of its (nonzero) digits is 2016, while the sum is 34.

The spelling of 21111010021987 in words is "twenty-one trillion, one hundred eleven billion, ten million, twenty-one thousand, nine hundred eighty-seven".