21489621 has 8 divisors (see below), whose sum is σ = 28702464. Its totient is φ = 14301600.

The previous prime is 21489619. The next prime is 21489623. The reversal of 21489621 is 12698412.

It is an interprime number because it is at equal distance from previous prime (21489619) and next prime (21489623).

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

It is not a de Polignac number, because 21489621 - 2¹ = 21489619 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21489623) 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, 4080 + ... + 7721.

It is an arithmetic number, because the mean of its divisors is an integer number (3587808).

Almost surely, 2^21489621 is an apocalyptic number.

It is an amenable number.

21489621 is a deficient number, since it is larger than the sum of its proper divisors (7212843).

21489621 is a wasteful number, since it uses less digits than its factorization.

21489621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12411.

The product of its digits is 6912, while the sum is 33.

The square root of 21489621 is about 4635.6899162908. The cubic root of 21489621 is about 278.0201363880.

The spelling of 21489621 in words is "twenty-one million, four hundred eighty-nine thousand, six hundred twenty-one".