21582961 has 8 divisors (see below), whose sum is σ = 22017960. Its totient is φ = 21151872.

The previous prime is 21582949. The next prime is 21582971. The reversal of 21582961 is 16928512.

It can be written as a sum of positive squares in 4 ways, for example, as 4928400 + 16654561 = 2220^2 + 4081^2 .

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 21582961 - 2⁷ = 21582833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21582941) 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 7 ways as a sum of consecutive naturals, for example, 11775 + ... + 13483.

It is an arithmetic number, because the mean of its divisors is an integer number (2752245).

Almost surely, 2^21582961 is an apocalyptic number.

It is an amenable number.

21582961 is a deficient number, since it is larger than the sum of its proper divisors (434999).

21582961 is a wasteful number, since it uses less digits than its factorization.

21582961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1955.

The product of its digits is 8640, while the sum is 34.

The square root of 21582961 is about 4645.7465492642. The cubic root of 21582961 is about 278.4220810934.

The spelling of 21582961 in words is "twenty-one million, five hundred eighty-two thousand, nine hundred sixty-one".