21989005 has 16 divisors (see below), whose sum is σ = 27086400. Its totient is φ = 17130880.

The previous prime is 21988999. The next prime is 21989017. The reversal of 21989005 is 50098912.

It is not a de Polignac number, because 21989005 - 2¹¹ = 21986957 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38361 + ... + 38929.

It is an arithmetic number, because the mean of its divisors is an integer number (1692900).

Almost surely, 2^21989005 is an apocalyptic number.

It is an amenable number.

21989005 is a deficient number, since it is larger than the sum of its proper divisors (5097395).

21989005 is a wasteful number, since it uses less digits than its factorization.

21989005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 764.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 21989005 is about 4689.2435424064. The cubic root of 21989005 is about 280.1572458591.

The spelling of 21989005 in words is "twenty-one million, nine hundred eighty-nine thousand, five".