21795681 has 4 divisors (see below), whose sum is σ = 29060912. Its totient is φ = 14530452.

The previous prime is 21795677. The next prime is 21795691. The reversal of 21795681 is 18659712.

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 not a de Polignac number, because 21795681 - 2² = 21795677 is a prime.

It is a super-2 number, since 2×21795681² = 950103420507522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21795601) 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, 3632611 + ... + 3632616.

It is an arithmetic number, because the mean of its divisors is an integer number (7265228).

Almost surely, 2^21795681 is an apocalyptic number.

It is an amenable number.

21795681 is a deficient number, since it is larger than the sum of its proper divisors (7265231).

21795681 is an equidigital number, since it uses as much as digits as its factorization.

21795681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7265230.

The product of its digits is 30240, while the sum is 39.

The square root of 21795681 is about 4668.5844749774. The cubic root of 21795681 is about 279.3337945524. Note that the first 3 decimals are identical.

The spelling of 21795681 in words is "twenty-one million, seven hundred ninety-five thousand, six hundred eighty-one".