21951824 has 10 divisors (see below), whose sum is σ = 42531690. Its totient is φ = 10975904.

The previous prime is 21951817. The next prime is 21951827. The reversal of 21951824 is 42815912.

It can be written as a sum of positive squares in only one way, i.e., 17372224 + 4579600 = 4168^2 + 2140^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21951827) 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 as a sum of consecutive naturals, namely, 685979 + ... + 686010.

It is an arithmetic number, because the mean of its divisors is an integer number (4253169).

Almost surely, 2^21951824 is an apocalyptic number.

It is an amenable number.

21951824 is a deficient number, since it is larger than the sum of its proper divisors (20579866).

21951824 is a wasteful number, since it uses less digits than its factorization.

21951824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1371997 (or 1371991 counting only the distinct ones).

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

The square root of 21951824 is about 4685.2773663893. The cubic root of 21951824 is about 279.9992516987. Note that the first 3 decimals are identical.

The spelling of 21951824 in words is "twenty-one million, nine hundred fifty-one thousand, eight hundred twenty-four".