21127889 has 4 divisors (see below), whose sum is σ = 22370724. Its totient is φ = 19885056.

The previous prime is 21127877. The next prime is 21127901. The reversal of 21127889 is 98872112.

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

It is an interprime number because it is at equal distance from previous prime (21127877) and next prime (21127901).

It can be written as a sum of positive squares in 2 ways, for example, as 14326225 + 6801664 = 3785^2 + 2608^2 .

It is a cyclic number.

It is not a de Polignac number, because 21127889 - 2⁸ = 21127633 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21127819) 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, 621392 + ... + 621425.

It is an arithmetic number, because the mean of its divisors is an integer number (5592681).

Almost surely, 2^21127889 is an apocalyptic number.

It is an amenable number.

21127889 is a deficient number, since it is larger than the sum of its proper divisors (1242835).

21127889 is a wasteful number, since it uses less digits than its factorization.

21127889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242834.

The product of its digits is 16128, while the sum is 38.

The square root of 21127889 is about 4596.5083487360. The cubic root of 21127889 is about 276.4513417903.

It can be divided in two parts, 2112 and 7889, that added together give a palindrome (10001).

The spelling of 21127889 in words is "twenty-one million, one hundred twenty-seven thousand, eight hundred eighty-nine".