21821954 has 48 divisors (see below), whose sum is σ = 42944256. Its totient is φ = 8215200.

The previous prime is 21821953. The next prime is 21821977. The reversal of 21821954 is 45912812.

It is a self number, because there is not a number n which added to its sum of digits gives 21821954.

It is not an unprimeable number, because it can be changed into a prime (21821953) 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 23 ways as a sum of consecutive naturals, for example, 33092 + ... + 33744.

It is an arithmetic number, because the mean of its divisors is an integer number (894672).

Almost surely, 2^21821954 is an apocalyptic number.

21821954 is a deficient number, since it is larger than the sum of its proper divisors (21122302).

21821954 is a wasteful number, since it uses less digits than its factorization.

21821954 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711 (or 704 counting only the distinct ones).

The product of its digits is 5760, while the sum is 32.

The square root of 21821954 is about 4671.3974354576. The cubic root of 21821954 is about 279.4459878798.

The spelling of 21821954 in words is "twenty-one million, eight hundred twenty-one thousand, nine hundred fifty-four".