21434581 has 8 divisors (see below), whose sum is σ = 25159040. Its totient is φ = 17875728.

The previous prime is 21434579. The next prime is 21434587. The reversal of 21434581 is 18543412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21434581 - 2¹ = 21434579 is a prime.

It is a super-2 number, since 2×21434581² = 918882525291122, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21434587) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 41121 + ... + 41638.

It is an arithmetic number, because the mean of its divisors is an integer number (3144880).

Almost surely, 2^21434581 is an apocalyptic number.

It is an amenable number.

21434581 is a deficient number, since it is larger than the sum of its proper divisors (3724459).

21434581 is an equidigital number, since it uses as much as digits as its factorization.

21434581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82803.

The product of its digits is 3840, while the sum is 28.

The square root of 21434581 is about 4629.7495612614. The cubic root of 21434581 is about 277.7825750223.

Adding to 21434581 its reverse (18543412), we get a palindrome (39977993).

It can be divided in two parts, 2143 and 4581, that added together give a square (6724 = 82²).

The spelling of 21434581 in words is "twenty-one million, four hundred thirty-four thousand, five hundred eighty-one".