221221999987 has 2 divisors, whose sum is σ = 221221999988. Its totient is φ = 221221999986.

The previous prime is 221221999981. The next prime is 221222000047. The reversal of 221221999987 is 789999122122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221221999987 - 2²⁷ = 221087782259 is a prime.

It is not a weakly prime, because it can be changed into another prime (221221999981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110610999993 + 110610999994.

It is an arithmetic number, because the mean of its divisors is an integer number (110610999994).

Almost surely, 2^221221999987 is an apocalyptic number.

221221999987 is a deficient number, since it is larger than the sum of its proper divisors (1).

221221999987 is an equidigital number, since it uses as much as digits as its factorization.

221221999987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5878656, while the sum is 61.

The spelling of 221221999987 in words is "two hundred twenty-one billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred eighty-seven".