21889081 has 4 divisors (see below), whose sum is σ = 23176692. Its totient is φ = 20601472.

The previous prime is 21889079. The next prime is 21889093. The reversal of 21889081 is 18098812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9357481 + 12531600 = 3059^2 + 3540^2 .

It is a cyclic number.

It is not a de Polignac number, because 21889081 - 2¹ = 21889079 is a prime.

It is a super-2 number, since 2×21889081² = 958263734049122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21889081.

It is not an unprimeable number, because it can be changed into a prime (21889001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 643780 + ... + 643813.

It is an arithmetic number, because the mean of its divisors is an integer number (5794173).

Almost surely, 2^21889081 is an apocalyptic number.

It is an amenable number.

21889081 is a deficient number, since it is larger than the sum of its proper divisors (1287611).

21889081 is a wasteful number, since it uses less digits than its factorization.

21889081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1287610.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 21889081 is about 4678.5768135193. The cubic root of 21889081 is about 279.7322312547.

The spelling of 21889081 in words is "twenty-one million, eight hundred eighty-nine thousand, eighty-one".