21211199987 has 2 divisors, whose sum is σ = 21211199988. Its totient is φ = 21211199986.

The previous prime is 21211199941. The next prime is 21211200011. The reversal of 21211199987 is 78999111212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21211199987 - 2¹⁴ = 21211183603 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211199927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605599993 + 10605599994.

It is an arithmetic number, because the mean of its divisors is an integer number (10605599994).

Almost surely, 2^21211199987 is an apocalyptic number.

21211199987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211199987 is an equidigital number, since it uses as much as digits as its factorization.

21211199987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 50.

The spelling of 21211199987 in words is "twenty-one billion, two hundred eleven million, one hundred ninety-nine thousand, nine hundred eighty-seven".