21561461 has 8 divisors (see below), whose sum is σ = 22310400. Its totient is φ = 20815920.

The previous prime is 21561443. The next prime is 21561469. The reversal of 21561461 is 16416512.

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 21561461 - 2¹⁴ = 21545077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21561461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21561469) 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, 25280 + ... + 26118.

It is an arithmetic number, because the mean of its divisors is an integer number (2788800).

Almost surely, 2^21561461 is an apocalyptic number.

It is an amenable number.

21561461 is a deficient number, since it is larger than the sum of its proper divisors (748939).

21561461 is an equidigital number, since it uses as much as digits as its factorization.

21561461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1699.

The product of its digits is 1440, while the sum is 26.

The square root of 21561461 is about 4643.4320281447. The cubic root of 21561461 is about 278.3295997523.

Adding to 21561461 its reverse (16416512), we get a palindrome (37977973).

It can be divided in two parts, 21561 and 461, that added together give a palindrome (22022).

The spelling of 21561461 in words is "twenty-one million, five hundred sixty-one thousand, four hundred sixty-one".