20831421 has 16 divisors (see below), whose sum is σ = 30030336. Its totient is φ = 12768576.

The previous prime is 20831323. The next prime is 20831533. The reversal of 20831421 is 12413802.

It is not a de Polignac number, because 20831421 - 2¹⁴ = 20815037 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20831621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10516 + ... + 12338.

It is an arithmetic number, because the mean of its divisors is an integer number (1876896).

Almost surely, 2^20831421 is an apocalyptic number.

It is an amenable number.

20831421 is a deficient number, since it is larger than the sum of its proper divisors (9198915).

20831421 is a wasteful number, since it uses less digits than its factorization.

20831421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2132.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 20831421 is about 4564.1451554481. The cubic root of 20831421 is about 275.1521846362.

It can be divided in two parts, 208314 and 21, that added together give a triangular number (208335 = T₆₄₅).

The spelling of 20831421 in words is "twenty million, eight hundred thirty-one thousand, four hundred twenty-one".