21280061 has 8 divisors (see below), whose sum is σ = 23608800. Its totient is φ = 19017040.

The previous prime is 21280013. The next prime is 21280067. The reversal of 21280061 is 16008212.

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 21280061 - 2¹⁴ = 21263677 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15746 + ... + 17043.

It is an arithmetic number, because the mean of its divisors is an integer number (2951100).

Almost surely, 2^21280061 is an apocalyptic number.

It is an amenable number.

21280061 is a deficient number, since it is larger than the sum of its proper divisors (2328739).

21280061 is a wasteful number, since it uses less digits than its factorization.

21280061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32859.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21280061 is about 4613.0316495771. The cubic root of 21280061 is about 277.1134612324.

Adding to 21280061 its reverse (16008212), we get a palindrome (37288273).

It can be divided in two parts, 21 and 280061, that added together give a palindrome (280082).

The spelling of 21280061 in words is "twenty-one million, two hundred eighty thousand, sixty-one".