21431140 has 24 divisors (see below), whose sum is σ = 46223352. Its totient is φ = 8340480.

The previous prime is 21431131. The next prime is 21431141. The reversal of 21431140 is 4113412.

It can be written as a sum of positive squares in 4 ways, for example, as 11546404 + 9884736 = 3398^2 + 3144^2 .

It is not an unprimeable number, because it can be changed into a prime (21431141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13741 + ... + 15220.

It is an arithmetic number, because the mean of its divisors is an integer number (1925973).

Almost surely, 2^21431140 is an apocalyptic number.

21431140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21431140 is an abundant number, since it is smaller than the sum of its proper divisors (24792212).

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

21431140 is a wasteful number, since it uses less digits than its factorization.

21431140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29007 (or 29005 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21431140 is about 4629.3779279726. The cubic root of 21431140 is about 277.7677096203.

Adding to 21431140 its reverse (4113412), we get a palindrome (25544552).

The spelling of 21431140 in words is "twenty-one million, four hundred thirty-one thousand, one hundred forty".