21212889 has 24 divisors (see below), whose sum is σ = 30798240. Its totient is φ = 12977664.

The previous prime is 21212887. The next prime is 21212899. The reversal of 21212889 is 98821212.

It is not a de Polignac number, because 21212889 - 2¹ = 21212887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21212887) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36997 + ... + 37565.

It is an arithmetic number, because the mean of its divisors is an integer number (1283260).

Almost surely, 2^21212889 is an apocalyptic number.

It is an amenable number.

21212889 is a deficient number, since it is larger than the sum of its proper divisors (9585351).

21212889 is a wasteful number, since it uses less digits than its factorization.

21212889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 649 (or 632 counting only the distinct ones).

The product of its digits is 4608, while the sum is 33.

The square root of 21212889 is about 4605.7452165746. The cubic root of 21212889 is about 276.8215778965.

The spelling of 21212889 in words is "twenty-one million, two hundred twelve thousand, eight hundred eighty-nine".