21423045 has 24 divisors (see below), whose sum is σ = 39874464. Its totient is φ = 9793056.

The previous prime is 21423019. The next prime is 21423053. The reversal of 21423045 is 54032412.

It is not a de Polignac number, because 21423045 - 2¹⁰ = 21422021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13839 + ... + 15308.

It is an arithmetic number, because the mean of its divisors is an integer number (1661436).

Almost surely, 2^21423045 is an apocalyptic number.

It is an amenable number.

21423045 is a deficient number, since it is larger than the sum of its proper divisors (18451419).

21423045 is a wasteful number, since it uses less digits than its factorization.

21423045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29169 (or 29162 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21423045 is about 4628.5035378619. The cubic root of 21423045 is about 277.7327322808.

Adding to 21423045 its reverse (54032412), we get a palindrome (75455457).

The spelling of 21423045 in words is "twenty-one million, four hundred twenty-three thousand, forty-five".