21060891 has 10 divisors (see below), whose sum is σ = 31461452. Its totient is φ = 14040540.

The previous prime is 21060889. The next prime is 21060899. The reversal of 21060891 is 19806012.

It is not a de Polignac number, because 21060891 - 2¹ = 21060889 is a prime.

It is a super-2 number, since 2×21060891² = 887122259427762, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21060899) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 129925 + ... + 130086.

Almost surely, 2^21060891 is an apocalyptic number.

21060891 is a deficient number, since it is larger than the sum of its proper divisors (10400561).

21060891 is an equidigital number, since it uses as much as digits as its factorization.

21060891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260023 (or 260014 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 21060891 is about 4589.2146386936. The cubic root of 21060891 is about 276.1588169131.

The spelling of 21060891 in words is "twenty-one million, sixty thousand, eight hundred ninety-one".