21261885 has 8 divisors (see below), whose sum is σ = 34019040. Its totient is φ = 11339664.

The previous prime is 21261871. The next prime is 21261887. The reversal of 21261885 is 58816212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21261885 - 2⁴ = 21261869 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261887) 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, 708715 + ... + 708744.

It is an arithmetic number, because the mean of its divisors is an integer number (4252380).

Almost surely, 2^21261885 is an apocalyptic number.

It is an amenable number.

21261885 is a deficient number, since it is larger than the sum of its proper divisors (12757155).

21261885 is a wasteful number, since it uses less digits than its factorization.

21261885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1417467.

The product of its digits is 7680, while the sum is 33.

The square root of 21261885 is about 4611.0611576946. The cubic root of 21261885 is about 277.0345415183.

The spelling of 21261885 in words is "twenty-one million, two hundred sixty-one thousand, eight hundred eighty-five".