21287489999 has 2 divisors, whose sum is σ = 21287490000. Its totient is φ = 21287489998.

The previous prime is 21287489983. The next prime is 21287490011. The reversal of 21287489999 is 99998478212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21287489999 - 2⁴ = 21287489983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21287489969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10643744999 + 10643745000.

It is an arithmetic number, because the mean of its divisors is an integer number (10643745000).

Almost surely, 2^21287489999 is an apocalyptic number.

21287489999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21287489999 is an equidigital number, since it uses as much as digits as its factorization.

21287489999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47029248, while the sum is 68.

The spelling of 21287489999 in words is "twenty-one billion, two hundred eighty-seven million, four hundred eighty-nine thousand, nine hundred ninety-nine".