21211201987 has 2 divisors, whose sum is σ = 21211201988. Its totient is φ = 21211201986.

The previous prime is 21211201939. The next prime is 21211202099. The reversal of 21211201987 is 78910211212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21211201987 - 2⁷ = 21211201859 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211201387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605600993 + 10605600994.

It is an arithmetic number, because the mean of its divisors is an integer number (10605600994).

Almost surely, 2^21211201987 is an apocalyptic number.

21211201987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211201987 is an equidigital number, since it uses as much as digits as its factorization.

21211201987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 34.

The spelling of 21211201987 in words is "twenty-one billion, two hundred eleven million, two hundred one thousand, nine hundred eighty-seven".