21209058 has 48 divisors (see below), whose sum is σ = 49827960. Its totient is φ = 6481152.

The previous prime is 21209033. The next prime is 21209077. The reversal of 21209058 is 85090212.

It can be written as a sum of positive squares in 4 ways, for example, as 8485569 + 12723489 = 2913^2 + 3567^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 54328 + ... + 54716.

Almost surely, 2^21209058 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21209058, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24913980).

21209058 is an abundant number, since it is smaller than the sum of its proper divisors (28618902).

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

21209058 is a wasteful number, since it uses less digits than its factorization.

21209058 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 640 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 21209058 is about 4605.3293041866. The cubic root of 21209058 is about 276.8049124419.

The spelling of 21209058 in words is "twenty-one million, two hundred nine thousand, fifty-eight".