212121109987 has 4 divisors (see below), whose sum is σ = 212812058536. Its totient is φ = 211430161440.

The previous prime is 212121109979. The next prime is 212121109997. The reversal of 212121109987 is 789901121212.

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 212121109987 - 2³ = 212121109979 is a prime.

It is a super-2 number, since 2×212121109987² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (212121109997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 345473814 + ... + 345474427.

It is an arithmetic number, because the mean of its divisors is an integer number (53203014634).

Almost surely, 2^212121109987 is an apocalyptic number.

212121109987 is a deficient number, since it is larger than the sum of its proper divisors (690948549).

212121109987 is an equidigital number, since it uses as much as digits as its factorization.

212121109987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 690948548.

The product of its (nonzero) digits is 36288, while the sum is 43.

The spelling of 212121109987 in words is "two hundred twelve billion, one hundred twenty-one million, one hundred nine thousand, nine hundred eighty-seven".