21431436 has 96 divisors (see below), whose sum is σ = 57200640. Its totient is φ = 6200064.

The previous prime is 21431401. The next prime is 21431489. The reversal of 21431436 is 63413412.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 271245 + ... + 271323.

It is an arithmetic number, because the mean of its divisors is an integer number (595840).

Almost surely, 2^21431436 is an apocalyptic number.

21431436 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21431436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28600320).

21431436 is an abundant number, since it is smaller than the sum of its proper divisors (35769204).

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

21431436 is a wasteful number, since it uses less digits than its factorization.

21431436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183 (or 181 counting only the distinct ones).

The product of its digits is 1728, while the sum is 24.

The square root of 21431436 is about 4629.4098976003. The cubic root of 21431436 is about 277.7689884271.

Adding to 21431436 its reverse (63413412), we get a palindrome (84844848).

The spelling of 21431436 in words is "twenty-one million, four hundred thirty-one thousand, four hundred thirty-six".