21989893 has 2 divisors, whose sum is σ = 21989894. Its totient is φ = 21989892.

The previous prime is 21989879. The next prime is 21989911. The reversal of 21989893 is 39898912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14493249 + 7496644 = 3807^2 + 2738^2 .

It is a cyclic number.

It is not a de Polignac number, because 21989893 - 2⁵ = 21989861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21989833) 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 as a sum of consecutive naturals, namely, 10994946 + 10994947.

It is an arithmetic number, because the mean of its divisors is an integer number (10994947).

Almost surely, 2^21989893 is an apocalyptic number.

It is an amenable number.

21989893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21989893 is an equidigital number, since it uses as much as digits as its factorization.

21989893 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 279936, while the sum is 49.

The square root of 21989893 is about 4689.3382262319. The cubic root of 21989893 is about 280.1610170815.

The spelling of 21989893 in words is "twenty-one million, nine hundred eighty-nine thousand, eight hundred ninety-three".