21123170 has 16 divisors (see below), whose sum is σ = 38257920. Its totient is φ = 8396784.

The previous prime is 21123161. The next prime is 21123173. The reversal of 21123170 is 7132112.

It is not an unprimeable number, because it can be changed into a prime (21123173) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4850 + ... + 8109.

It is an arithmetic number, because the mean of its divisors is an integer number (2391120).

Almost surely, 2^21123170 is an apocalyptic number.

21123170 is a deficient number, since it is larger than the sum of its proper divisors (17134750).

21123170 is a wasteful number, since it uses less digits than its factorization.

21123170 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13129.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21123170 is about 4595.9949956457. The cubic root of 21123170 is about 276.4307580803.

Adding to 21123170 its reverse (7132112), we get a palindrome (28255282).

The spelling of 21123170 in words is "twenty-one million, one hundred twenty-three thousand, one hundred seventy".