21136081 has 8 divisors (see below), whose sum is σ = 21454400. Its totient is φ = 20820240.

The previous prime is 21136069. The next prime is 21136123. The reversal of 21136081 is 18063112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21136081 - 2¹⁷ = 21005009 is a prime.

It is a super-2 number, since 2×21136081² = 893467840077122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21136481) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22540 + ... + 23458.

It is an arithmetic number, because the mean of its divisors is an integer number (2681800).

Almost surely, 2^21136081 is an apocalyptic number.

It is an amenable number.

21136081 is a deficient number, since it is larger than the sum of its proper divisors (318319).

21136081 is a wasteful number, since it uses less digits than its factorization.

21136081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1239.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21136081 is about 4597.3993735589. The cubic root of 21136081 is about 276.4870670310.

Adding to 21136081 its reverse (18063112), we get a palindrome (39199193).

The spelling of 21136081 in words is "twenty-one million, one hundred thirty-six thousand, eighty-one".