21041387 has 2 divisors, whose sum is σ = 21041388. Its totient is φ = 21041386.

The previous prime is 21041381. The next prime is 21041407. The reversal of 21041387 is 78314012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21041387 - 2²⁴ = 4264171 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21041381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520693 + 10520694.

It is an arithmetic number, because the mean of its divisors is an integer number (10520694).

Almost surely, 2^21041387 is an apocalyptic number.

21041387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21041387 is an equidigital number, since it uses as much as digits as its factorization.

21041387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21041387 is about 4587.0891641650. The cubic root of 21041387 is about 276.0735425040.

Adding to 21041387 its reverse (78314012), we get a palindrome (99355399).

The spelling of 21041387 in words is "twenty-one million, forty-one thousand, three hundred eighty-seven".