21712404 has 48 divisors (see below), whose sum is σ = 59004288. Its totient is φ = 6085248.

The previous prime is 21712393. The next prime is 21712423. The reversal of 21712404 is 40421712.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2014 + ... + 6890.

It is an arithmetic number, because the mean of its divisors is an integer number (1229256).

Almost surely, 2^21712404 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21712404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29502144).

21712404 is an abundant number, since it is smaller than the sum of its proper divisors (37291884).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21712404 is a wasteful number, since it uses less digits than its factorization.

21712404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4944 (or 4942 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 21712404 is about 4659.6570689269. The cubic root of 21712404 is about 278.9775807065.

It can be divided in two parts, 217 and 12404, that added together give a palindrome (12621).

The spelling of 21712404 in words is "twenty-one million, seven hundred twelve thousand, four hundred four".