21489577 has 4 divisors (see below), whose sum is σ = 21523140. Its totient is φ = 21456016.

The previous prime is 21489557. The next prime is 21489583. The reversal of 21489577 is 77598412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11978521 + 9511056 = 3461^2 + 3084^2 .

It is a cyclic number.

It is not a de Polignac number, because 21489577 - 2⁷ = 21489449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21489557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15802 + ... + 17107.

It is an arithmetic number, because the mean of its divisors is an integer number (5380785).

Almost surely, 2^21489577 is an apocalyptic number.

It is an amenable number.

21489577 is a deficient number, since it is larger than the sum of its proper divisors (33563).

21489577 is an equidigital number, since it uses as much as digits as its factorization.

21489577 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33562.

The product of its digits is 141120, while the sum is 43.

The square root of 21489577 is about 4635.6851705007. The cubic root of 21489577 is about 278.0199466391.

The spelling of 21489577 in words is "twenty-one million, four hundred eighty-nine thousand, five hundred seventy-seven".