21760891 has 4 divisors (see below), whose sum is σ = 21805000. Its totient is φ = 21716784.

The previous prime is 21760889. The next prime is 21760897. The reversal of 21760891 is 19806712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21760891 - 2¹ = 21760889 is a prime.

It is a super-2 number, since 2×21760891² = 947072754227762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21760897) 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 3 ways as a sum of consecutive naturals, for example, 21306 + ... + 22303.

It is an arithmetic number, because the mean of its divisors is an integer number (5451250).

Almost surely, 2^21760891 is an apocalyptic number.

21760891 is a deficient number, since it is larger than the sum of its proper divisors (44109).

21760891 is an equidigital number, since it uses as much as digits as its factorization.

21760891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44108.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 21760891 is about 4664.8570181732. The cubic root of 21760891 is about 279.1850923409.

The spelling of 21760891 in words is "twenty-one million, seven hundred sixty thousand, eight hundred ninety-one".