21010871 has 4 divisors (see below), whose sum is σ = 24012432. Its totient is φ = 18009312.

The previous prime is 21010859. The next prime is 21010883. The reversal of 21010871 is 17801012.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21010859) and next prime (21010883).

It is a cyclic number.

It is not a de Polignac number, because 21010871 - 2¹⁸ = 20748727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1500770 + ... + 1500783.

It is an arithmetic number, because the mean of its divisors is an integer number (6003108).

Almost surely, 2^21010871 is an apocalyptic number.

21010871 is a deficient number, since it is larger than the sum of its proper divisors (3001561).

21010871 is an equidigital number, since it uses as much as digits as its factorization.

21010871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3001560.

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 21010871 is about 4583.7616648338. The cubic root of 21010871 is about 275.9400161951.

Adding to 21010871 its reverse (17801012), we get a palindrome (38811883).

The spelling of 21010871 in words is "twenty-one million, ten thousand, eight hundred seventy-one".