21036989 has 4 divisors (see below), whose sum is σ = 21303360. Its totient is φ = 20770620.

The previous prime is 21036959. The next prime is 21036991. The reversal of 21036989 is 98963012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21036989 is a prime.

It is a super-2 number, since 2×21036989² = 885109812372242, which contains 22 as substring.

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

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036929) 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, 133067 + ... + 133224.

It is an arithmetic number, because the mean of its divisors is an integer number (5325840).

Almost surely, 2^21036989 is an apocalyptic number.

It is an amenable number.

21036989 is a deficient number, since it is larger than the sum of its proper divisors (266371).

21036989 is an equidigital number, since it uses as much as digits as its factorization.

21036989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266370.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21036989 is about 4586.6097501314. The cubic root of 21036989 is about 276.0543065091.

The spelling of 21036989 in words is "twenty-one million, thirty-six thousand, nine hundred eighty-nine".