21123675 has 36 divisors (see below), whose sum is σ = 38094784. Its totient is φ = 11188800.

The previous prime is 21123653. The next prime is 21123677. The reversal of 21123675 is 57632112.

It is a happy number.

It is not a de Polignac number, because 21123675 - 2⁵ = 21123643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 49965 + ... + 50385.

Almost surely, 2^21123675 is an apocalyptic number.

21123675 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21123675 is a deficient number, since it is larger than the sum of its proper divisors (16971109).

21123675 is a wasteful number, since it uses less digits than its factorization.

21123675 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660 (or 652 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21123675 is about 4596.0499344546. The cubic root of 21123675 is about 276.4329609760.

Adding to 21123675 its reverse (57632112), we get a palindrome (78755787).

The spelling of 21123675 in words is "twenty-one million, one hundred twenty-three thousand, six hundred seventy-five".