21431400 has 96 divisors (see below), whose sum is σ = 69370560. Its totient is φ = 5463040.

The previous prime is 21431387. The next prime is 21431401. The reversal of 21431400 is 413412.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21431400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13024 + ... + 14576.

It is an arithmetic number, because the mean of its divisors is an integer number (722610).

Almost surely, 2^21431400 is an apocalyptic number.

21431400 is a gapful number since it is divisible by the number (20) 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 21431400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34685280).

21431400 is an abundant number, since it is smaller than the sum of its proper divisors (47939160).

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

21431400 is a wasteful number, since it uses less digits than its factorization.

21431400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1595 (or 1586 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21431400 is about 4629.4060094142. The cubic root of 21431400 is about 277.7688328971.

Adding to 21431400 its reverse (413412), we get a palindrome (21844812).

The spelling of 21431400 in words is "twenty-one million, four hundred thirty-one thousand, four hundred".