21123039 has 32 divisors (see below), whose sum is σ = 33997824. Its totient is φ = 11404800.

The previous prime is 21123029. The next prime is 21123043. The reversal of 21123039 is 93032112.

It is a happy number.

It is not a de Polignac number, because 21123039 - 2⁷ = 21122911 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123029) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48567 + ... + 48999.

It is an arithmetic number, because the mean of its divisors is an integer number (1062432).

Almost surely, 2^21123039 is an apocalyptic number.

21123039 is a deficient number, since it is larger than the sum of its proper divisors (12874785).

21123039 is a wasteful number, since it uses less digits than its factorization.

21123039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 21123039 is about 4595.9807440850. The cubic root of 21123039 is about 276.4301866304.

It can be divided in two parts, 2112 and 3039, that added together give a triangular number (5151 = T₁₀₁).

The spelling of 21123039 in words is "twenty-one million, one hundred twenty-three thousand, thirty-nine".