21088011 has 16 divisors (see below), whose sum is σ = 32742144. Its totient is φ = 11822304.

The previous prime is 21088009. The next prime is 21088013. The reversal of 21088011 is 11088012.

It is an interprime number because it is at equal distance from previous prime (21088009) and next prime (21088013).

It is not a de Polignac number, because 21088011 - 2¹ = 21088009 is a prime.

It is a super-2 number, since 2×21088011² = 889408415872242, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21088013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8361 + ... + 10586.

It is an arithmetic number, because the mean of its divisors is an integer number (2046384).

Almost surely, 2^21088011 is an apocalyptic number.

21088011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21088011 is a deficient number, since it is larger than the sum of its proper divisors (11654133).

21088011 is a wasteful number, since it uses less digits than its factorization.

21088011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19010.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 21088011 is about 4592.1684420326. The cubic root of 21088011 is about 276.2773021616.

Subtracting from 21088011 its reverse (11088012), we obtain a palindrome (9999999).

The spelling of 21088011 in words is "twenty-one million, eighty-eight thousand, eleven".