21340881 has 8 divisors (see below), whose sum is σ = 31616160. Its totient is φ = 14227236.

The previous prime is 21340861. The next prime is 21340883. The reversal of 21340881 is 18804312.

It is not a de Polignac number, because 21340881 - 2¹¹ = 21338833 is a prime.

It is a super-2 number, since 2×21340881² = 910866403712322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 790403 = 21340881 / (2 + 1 + 3 + 4 + 0 + 8 + 8 + 1).

It is not an unprimeable number, because it can be changed into a prime (21340883) 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 7 ways as a sum of consecutive naturals, for example, 395175 + ... + 395228.

It is an arithmetic number, because the mean of its divisors is an integer number (3952020).

Almost surely, 2^21340881 is an apocalyptic number.

It is an amenable number.

21340881 is a deficient number, since it is larger than the sum of its proper divisors (10275279).

21340881 is an equidigital number, since it uses as much as digits as its factorization.

21340881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 790412 (or 790406 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21340881 is about 4619.6191401456. The cubic root of 21340881 is about 277.3772137573.

The spelling of 21340881 in words is "twenty-one million, three hundred forty thousand, eight hundred eighty-one".