21789423 has 6 divisors (see below), whose sum is σ = 31473624. Its totient is φ = 14526276.

The previous prime is 21789421. The next prime is 21789463. The reversal of 21789423 is 32498712.

It is not a de Polignac number, because 21789423 - 2¹ = 21789421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21789421) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1210515 + ... + 1210532.

It is an arithmetic number, because the mean of its divisors is an integer number (5245604).

Almost surely, 2^21789423 is an apocalyptic number.

21789423 is a deficient number, since it is larger than the sum of its proper divisors (9684201).

21789423 is a wasteful number, since it uses less digits than its factorization.

21789423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2421053 (or 2421050 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21789423 is about 4667.9142022964. The cubic root of 21789423 is about 279.3070577842.

The spelling of 21789423 in words is "twenty-one million, seven hundred eighty-nine thousand, four hundred twenty-three".