20891011 has 4 divisors (see below), whose sum is σ = 22119912. Its totient is φ = 19662112.

The previous prime is 20891009. The next prime is 20891027. The reversal of 20891011 is 11019802.

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

It is a cyclic number.

It is not a de Polignac number, because 20891011 - 2¹ = 20891009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20891041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 614425 + ... + 614458.

It is an arithmetic number, because the mean of its divisors is an integer number (5529978).

Almost surely, 2^20891011 is an apocalyptic number.

20891011 is a deficient number, since it is larger than the sum of its proper divisors (1228901).

20891011 is a wasteful number, since it uses less digits than its factorization.

20891011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1228900.

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 20891011 is about 4570.6685506608. The cubic root of 20891011 is about 275.4143000426.

It can be divided in two parts, 208 and 91011, that added together give a palindrome (91219).

The spelling of 20891011 in words is "twenty million, eight hundred ninety-one thousand, eleven".