21053887 has 2 divisors, whose sum is σ = 21053888. Its totient is φ = 21053886.

The previous prime is 21053873. The next prime is 21053897. The reversal of 21053887 is 78835012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21053887 - 2¹¹ = 21051839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21053897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526943 + 10526944.

It is an arithmetic number, because the mean of its divisors is an integer number (10526944).

Almost surely, 2^21053887 is an apocalyptic number.

21053887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053887 is an equidigital number, since it uses as much as digits as its factorization.

21053887 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 21053887 is about 4588.4514817093. The cubic root of 21053887 is about 276.1282004368.

Adding to 21053887 its reverse (78835012), we get a palindrome (99888899).

The spelling of 21053887 in words is "twenty-one million, fifty-three thousand, eight hundred eighty-seven".