21245881 has 8 divisors (see below), whose sum is σ = 22525184. Its totient is φ = 20003760.

The previous prime is 21245867. The next prime is 21245911. The reversal of 21245881 is 18854212.

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 21245881 - 2⁵ = 21245849 is a prime.

It is a super-2 number, since 2×21245881² = 902774918932322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21245281) 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, 8115 + ... + 10408.

It is an arithmetic number, because the mean of its divisors is an integer number (2815648).

Almost surely, 2^21245881 is an apocalyptic number.

It is an amenable number.

21245881 is a deficient number, since it is larger than the sum of its proper divisors (1279303).

21245881 is a wasteful number, since it uses less digits than its factorization.

21245881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18591.

The product of its digits is 5120, while the sum is 31.

The square root of 21245881 is about 4609.3254387166. The cubic root of 21245881 is about 276.9650153265.

The spelling of 21245881 in words is "twenty-one million, two hundred forty-five thousand, eight hundred eighty-one".