21504621 has 8 divisors (see below), whose sum is σ = 28695744. Its totient is φ = 14324960.

The previous prime is 21504589. The next prime is 21504647. The reversal of 21504621 is 12640512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21504621 - 2⁵ = 21504589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21500621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3601 + ... + 7481.

It is an arithmetic number, because the mean of its divisors is an integer number (3586968).

Almost surely, 2^21504621 is an apocalyptic number.

It is an amenable number.

21504621 is a deficient number, since it is larger than the sum of its proper divisors (7191123).

21504621 is a wasteful number, since it uses less digits than its factorization.

21504621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5731.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21504621 is about 4637.3075162210. The cubic root of 21504621 is about 278.0848084160.

The spelling of 21504621 in words is "twenty-one million, five hundred four thousand, six hundred twenty-one".