21789139 has 4 divisors (see below), whose sum is σ = 22146400. Its totient is φ = 21431880.

The previous prime is 21789127. The next prime is 21789151. The reversal of 21789139 is 93198712.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21789127) and next prime (21789151).

It is a cyclic number.

It is not a de Polignac number, because 21789139 - 2¹³ = 21780947 is a prime.

It is a super-2 number, since 2×21789139² = 949533156722642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21789109) 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, 178539 + ... + 178660.

It is an arithmetic number, because the mean of its divisors is an integer number (5536600).

Almost surely, 2^21789139 is an apocalyptic number.

21789139 is a deficient number, since it is larger than the sum of its proper divisors (357261).

21789139 is an equidigital number, since it uses as much as digits as its factorization.

21789139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357260.

The product of its digits is 27216, while the sum is 40.

The square root of 21789139 is about 4667.8837817581. The cubic root of 21789139 is about 279.3058442971.

The spelling of 21789139 in words is "twenty-one million, seven hundred eighty-nine thousand, one hundred thirty-nine".