21876989 has 2 divisors, whose sum is σ = 21876990. Its totient is φ = 21876988.

The previous prime is 21876983. The next prime is 21876997. The reversal of 21876989 is 98967812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21780889 + 96100 = 4667^2 + 310^2 .

It is a cyclic number.

It is not a de Polignac number, because 21876989 - 2⁴ = 21876973 is a prime.

It is a super-2 number, since 2×21876989² = 957205295412242, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21876983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10938494 + 10938495.

It is an arithmetic number, because the mean of its divisors is an integer number (10938495).

Almost surely, 2^21876989 is an apocalyptic number.

It is an amenable number.

21876989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21876989 is an equidigital number, since it uses as much as digits as its factorization.

21876989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 50.

The square root of 21876989 is about 4677.2843616783. The cubic root of 21876989 is about 279.6807117294.

The spelling of 21876989 in words is "twenty-one million, eight hundred seventy-six thousand, nine hundred eighty-nine".