21448531 has 4 divisors (see below), whose sum is σ = 23098432. Its totient is φ = 19798632.

The previous prime is 21448523. The next prime is 21448561. The reversal of 21448531 is 13584412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21448531 - 2³ = 21448523 is a prime.

It is a super-2 number, since 2×21448531² = 920078964115922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21448531.

It is not an unprimeable number, because it can be changed into a prime (21448561) 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 3 ways as a sum of consecutive naturals, for example, 824931 + ... + 824956.

It is an arithmetic number, because the mean of its divisors is an integer number (5774608).

Almost surely, 2^21448531 is an apocalyptic number.

21448531 is a deficient number, since it is larger than the sum of its proper divisors (1649901).

21448531 is a wasteful number, since it uses less digits than its factorization.

21448531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1649900.

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

The square root of 21448531 is about 4631.2558771893. The cubic root of 21448531 is about 277.8428238724.

The spelling of 21448531 in words is "twenty-one million, four hundred forty-eight thousand, five hundred thirty-one".