21101887 has 2 divisors, whose sum is σ = 21101888. Its totient is φ = 21101886.

The previous prime is 21101869. The next prime is 21101903. The reversal of 21101887 is 78810112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21101887 - 2²³ = 12713279 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21101867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550943 + 10550944.

It is an arithmetic number, because the mean of its divisors is an integer number (10550944).

Almost surely, 2^21101887 is an apocalyptic number.

21101887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101887 is an equidigital number, since it uses as much as digits as its factorization.

21101887 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21101887 is about 4593.6790266626. The cubic root of 21101887 is about 276.3378860846.

Adding to 21101887 its reverse (78810112), we get a palindrome (99911999).

The spelling of 21101887 in words is "twenty-one million, one hundred one thousand, eight hundred eighty-seven".