21434440 has 16 divisors (see below), whose sum is σ = 48227580. Its totient is φ = 8573760.

The previous prime is 21434437. The next prime is 21434449. The reversal of 21434440 is 4443412.

It can be written as a sum of positive squares in 2 ways, for example, as 21178404 + 256036 = 4602^2 + 506^2 .

It is a super-2 number, since 2×21434440² = 918870436227200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21434449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 267891 + ... + 267970.

Almost surely, 2^21434440 is an apocalyptic number.

21434440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21434440 is an abundant number, since it is smaller than the sum of its proper divisors (26793140).

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

21434440 is a wasteful number, since it uses less digits than its factorization.

21434440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535872 (or 535868 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 21434440 is about 4629.7343336308. The cubic root of 21434440 is about 277.7819659220.

Adding to 21434440 its reverse (4443412), we get a palindrome (25877852).

The spelling of 21434440 in words is "twenty-one million, four hundred thirty-four thousand, four hundred forty".