21210999966 has 96 divisors (see below), whose sum is σ = 50558508000. Its totient is φ = 6386874624.

The previous prime is 21210999917. The next prime is 21210999973. The reversal of 21210999966 is 66999901212.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3158220 + ... + 3164928.

It is an arithmetic number, because the mean of its divisors is an integer number (526651125).

Almost surely, 2^21210999966 is an apocalyptic number.

21210999966 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21210999966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25279254000).

21210999966 is an abundant number, since it is smaller than the sum of its proper divisors (29347508034).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21210999966 is a wasteful number, since it uses less digits than its factorization.

21210999966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7018 (or 7015 counting only the distinct ones).

The product of its (nonzero) digits is 944784, while the sum is 54.

The spelling of 21210999966 in words is "twenty-one billion, two hundred ten million, nine hundred ninety-nine thousand, nine hundred sixty-six".