21031423 has 16 divisors (see below), whose sum is σ = 26122240. Its totient is φ = 16524000.

The previous prime is 21031421. The next prime is 21031433. The reversal of 21031423 is 32413012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21031423 - 2¹ = 21031421 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031397 and 21031406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1573 + ... + 6673.

It is an arithmetic number, because the mean of its divisors is an integer number (1632640).

Almost surely, 2^21031423 is an apocalyptic number.

21031423 is a deficient number, since it is larger than the sum of its proper divisors (5090817).

21031423 is a wasteful number, since it uses less digits than its factorization.

21031423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5158.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21031423 is about 4586.0029437409. The cubic root of 21031423 is about 276.0299580658.

Adding to 21031423 its reverse (32413012), we get a palindrome (53444435).

The spelling of 21031423 in words is "twenty-one million, thirty-one thousand, four hundred twenty-three".