21102481 has 2 divisors, whose sum is σ = 21102482. Its totient is φ = 21102480.

The previous prime is 21102467. The next prime is 21102493. The reversal of 21102481 is 18420112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12006225 + 9096256 = 3465^2 + 3016^2 .

It is a cyclic number.

It is not a de Polignac number, because 21102481 - 2¹⁷ = 20971409 is a prime.

It is a super-2 number, since 2×21102481² = 890629408710722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21102421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551240 + 10551241.

It is an arithmetic number, because the mean of its divisors is an integer number (10551241).

Almost surely, 2^21102481 is an apocalyptic number.

It is an amenable number.

21102481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102481 is an equidigital number, since it uses as much as digits as its factorization.

21102481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21102481 is about 4593.7436802678. The cubic root of 21102481 is about 276.3404789517.

Adding to 21102481 its reverse (18420112), we get a palindrome (39522593).

The spelling of 21102481 in words is "twenty-one million, one hundred two thousand, four hundred eighty-one".