21904461 has 6 divisors (see below), whose sum is σ = 31639790. Its totient is φ = 14602968.

The previous prime is 21904459. The next prime is 21904469. The reversal of 21904461 is 16440912.

21904461 is a `hidden beast` number, since 219 + 0 + 446 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21622500 + 281961 = 4650^2 + 531^2 .

It is not a de Polignac number, because 21904461 - 2¹ = 21904459 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904469) 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, 1216906 + ... + 1216923.

Almost surely, 2^21904461 is an apocalyptic number.

It is an amenable number.

21904461 is a deficient number, since it is larger than the sum of its proper divisors (9735329).

21904461 is a wasteful number, since it uses less digits than its factorization.

21904461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2433835 (or 2433832 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21904461 is about 4680.2201871280. The cubic root of 21904461 is about 279.7977323215.

The spelling of 21904461 in words is "twenty-one million, nine hundred four thousand, four hundred sixty-one".