21161238 has 48 divisors (see below), whose sum is σ = 49641984. Its totient is φ = 5995920.

The previous prime is 21161237. The next prime is 21161279. The reversal of 21161238 is 83216112.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48883 + ... + 49313.

It is an arithmetic number, because the mean of its divisors is an integer number (1034208).

Almost surely, 2^21161238 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21161238, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24820992).

21161238 is an abundant number, since it is smaller than the sum of its proper divisors (28480746).

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

21161238 is a wasteful number, since it uses less digits than its factorization.

21161238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 617 (or 610 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 21161238 is about 4600.1345632492. The cubic root of 21161238 is about 276.5967188213.

The spelling of 21161238 in words is "twenty-one million, one hundred sixty-one thousand, two hundred thirty-eight".