21921876 has 18 divisors (see below), whose sum is σ = 55413722. Its totient is φ = 7307280.

The previous prime is 21921869. The next prime is 21921899. The reversal of 21921876 is 67812912.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 853776 = 4590^2 + 924^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 608941 = 21921876 / (2 + 1 + 9 + 2 + 1 + 8 + 7 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 21921876.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 304435 + ... + 304506.

Almost surely, 2^21921876 is an apocalyptic number.

It is an amenable number.

21921876 is an abundant number, since it is smaller than the sum of its proper divisors (33491846).

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

21921876 is a wasteful number, since it uses less digits than its factorization.

21921876 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 608951 (or 608946 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21921876 is about 4682.0803068721. The cubic root of 21921876 is about 279.8718631382.

The spelling of 21921876 in words is "twenty-one million, nine hundred twenty-one thousand, eight hundred seventy-six".