21210999989 has 2 divisors, whose sum is σ = 21210999990. Its totient is φ = 21210999988.

The previous prime is 21210999973. The next prime is 21211000073. The reversal of 21210999989 is 98999901212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13912202500 + 7298797489 = 117950^2 + 85433^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210999989 - 2⁴ = 21210999973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210999889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605499994 + 10605499995.

It is an arithmetic number, because the mean of its divisors is an integer number (10605499995).

Almost surely, 2^21210999989 is an apocalyptic number.

It is an amenable number.

21210999989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210999989 is an equidigital number, since it uses as much as digits as its factorization.

21210999989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1889568, while the sum is 59.

The spelling of 21210999989 in words is "twenty-one billion, two hundred ten million, nine hundred ninety-nine thousand, nine hundred eighty-nine".