21260881 has 2 divisors, whose sum is σ = 21260882. Its totient is φ = 21260880.

The previous prime is 21260851. The next prime is 21260887. The reversal of 21260881 is 18806212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19184400 + 2076481 = 4380^2 + 1441^2 .

It is a cyclic number.

It is not a de Polignac number, because 21260881 - 2⁵ = 21260849 is a prime.

It is a super-2 number, since 2×21260881² = 904050121792322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21260887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630440 + 10630441.

It is an arithmetic number, because the mean of its divisors is an integer number (10630441).

Almost surely, 2^21260881 is an apocalyptic number.

It is an amenable number.

21260881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21260881 is an equidigital number, since it uses as much as digits as its factorization.

21260881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 21260881 is about 4610.9522877601. The cubic root of 21260881 is about 277.0301808661.

The spelling of 21260881 in words is "twenty-one million, two hundred sixty thousand, eight hundred eighty-one".