21989293 has 4 divisors (see below), whose sum is σ = 22005088. Its totient is φ = 21973500.

The previous prime is 21989291. The next prime is 21989369. The reversal of 21989293 is 39298912.

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 not a de Polignac number, because 21989293 - 2¹ = 21989291 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989291) 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, 5583 + ... + 8668.

It is an arithmetic number, because the mean of its divisors is an integer number (5501272).

Almost surely, 2^21989293 is an apocalyptic number.

It is an amenable number.

21989293 is a deficient number, since it is larger than the sum of its proper divisors (15795).

21989293 is a wasteful number, since it uses less digits than its factorization.

21989293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15794.

The product of its digits is 69984, while the sum is 43.

The square root of 21989293 is about 4689.2742508836. The cubic root of 21989293 is about 280.1584689694.

The spelling of 21989293 in words is "twenty-one million, nine hundred eighty-nine thousand, two hundred ninety-three".