21429903 has 16 divisors (see below), whose sum is σ = 31295232. Its totient is φ = 12936000.

The previous prime is 21429901. The next prime is 21429917. The reversal of 21429903 is 30992412.

It is not a de Polignac number, because 21429903 - 2¹ = 21429901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21429901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8118 + ... + 10428.

It is an arithmetic number, because the mean of its divisors is an integer number (1955952).

Almost surely, 2^21429903 is an apocalyptic number.

21429903 is a deficient number, since it is larger than the sum of its proper divisors (9865329).

21429903 is a wasteful number, since it uses less digits than its factorization.

21429903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2606.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21429903 is about 4629.2443227810. The cubic root of 21429903 is about 277.7623652900.

It can be divided in two parts, 21 and 429903, that added together give a palindrome (429924).

The spelling of 21429903 in words is "twenty-one million, four hundred twenty-nine thousand, nine hundred three".