21465861 has 4 divisors (see below), whose sum is σ = 28621152. Its totient is φ = 14310572.

The previous prime is 21465841. The next prime is 21465863. The reversal of 21465861 is 16856412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21465861 - 2⁹ = 21465349 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465863) 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 3 ways as a sum of consecutive naturals, for example, 3577641 + ... + 3577646.

It is an arithmetic number, because the mean of its divisors is an integer number (7155288).

Almost surely, 2^21465861 is an apocalyptic number.

It is an amenable number.

21465861 is a deficient number, since it is larger than the sum of its proper divisors (7155291).

21465861 is an equidigital number, since it uses as much as digits as its factorization.

21465861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7155290.

The product of its digits is 11520, while the sum is 33.

The square root of 21465861 is about 4633.1264821932. The cubic root of 21465861 is about 277.9176342779.

The spelling of 21465861 in words is "twenty-one million, four hundred sixty-five thousand, eight hundred sixty-one".