21843531 has 6 divisors (see below), whose sum is σ = 31551780. Its totient is φ = 14562348.

The previous prime is 21843461. The next prime is 21843539. The reversal of 21843531 is 13534812.

It is a happy number.

It is not a de Polignac number, because 21843531 - 2⁷ = 21843403 is a prime.

It is a super-2 number, since 2×21843531² = 954279693095922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21843495 and 21843504.

It is not an unprimeable number, because it can be changed into a prime (21843539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1213521 + ... + 1213538.

It is an arithmetic number, because the mean of its divisors is an integer number (5258630).

Almost surely, 2^21843531 is an apocalyptic number.

21843531 is a deficient number, since it is larger than the sum of its proper divisors (9708249).

21843531 is a wasteful number, since it uses less digits than its factorization.

21843531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2427065 (or 2427062 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21843531 is about 4673.7063450756. The cubic root of 21843531 is about 279.5380605980.

The spelling of 21843531 in words is "twenty-one million, eight hundred forty-three thousand, five hundred thirty-one".