21613423 has 4 divisors (see below), whose sum is σ = 23276008. Its totient is φ = 19950840.

The previous prime is 21613421. The next prime is 21613433. The reversal of 21613423 is 32431612.

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

It is not a de Polignac number, because 21613423 - 2¹ = 21613421 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 21613394 and 21613403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613421) 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, 831273 + ... + 831298.

It is an arithmetic number, because the mean of its divisors is an integer number (5819002).

Almost surely, 2^21613423 is an apocalyptic number.

21613423 is a deficient number, since it is larger than the sum of its proper divisors (1662585).

21613423 is a wasteful number, since it uses less digits than its factorization.

21613423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1662584.

The product of its digits is 864, while the sum is 22.

The square root of 21613423 is about 4649.0238760411. The cubic root of 21613423 is about 278.5530070032.

The spelling of 21613423 in words is "twenty-one million, six hundred thirteen thousand, four hundred twenty-three".