21654913 has 6 divisors (see below), whose sum is σ = 25190466. Its totient is φ = 18561312.

The previous prime is 21654907. The next prime is 21654931. The reversal of 21654913 is 31945612.

It can be written as a sum of positive squares in only one way, i.e., 20638849 + 1016064 = 4543^2 + 1008^2 .

It is not a de Polignac number, because 21654913 - 2⁵ = 21654881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21654943) 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 5 ways as a sum of consecutive naturals, for example, 220920 + ... + 221017.

It is an arithmetic number, because the mean of its divisors is an integer number (4198411).

Almost surely, 2^21654913 is an apocalyptic number.

It is an amenable number.

21654913 is a deficient number, since it is larger than the sum of its proper divisors (3535553).

21654913 is an equidigital number, since it uses as much as digits as its factorization.

21654913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441951 (or 441944 counting only the distinct ones).

The product of its digits is 6480, while the sum is 31.

The square root of 21654913 is about 4653.4839636556. The cubic root of 21654913 is about 278.7311336075.

The spelling of 21654913 in words is "twenty-one million, six hundred fifty-four thousand, nine hundred thirteen".