21173039 has 4 divisors (see below), whose sum is σ = 21520200. Its totient is φ = 20825880.

The previous prime is 21173029. The next prime is 21173057. The reversal of 21173039 is 93037112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21173039 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21172999 and 21173017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21173029) 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, 173489 + ... + 173610.

It is an arithmetic number, because the mean of its divisors is an integer number (5380050).

Almost surely, 2^21173039 is an apocalyptic number.

21173039 is a deficient number, since it is larger than the sum of its proper divisors (347161).

21173039 is an equidigital number, since it uses as much as digits as its factorization.

21173039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347160.

The product of its (nonzero) digits is 1134, while the sum is 26.

The square root of 21173039 is about 4601.4170643401. The cubic root of 21173039 is about 276.6481258845.

The spelling of 21173039 in words is "twenty-one million, one hundred seventy-three thousand, thirty-nine".