21152681 has 8 divisors (see below), whose sum is σ = 24290400. Its totient is φ = 18217440.

The previous prime is 21152669. The next prime is 21152683. The reversal of 21152681 is 18625112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21152681 is a prime.

It is a super-2 number, since 2×21152681² = 894871826975522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21152681.

It is not an unprimeable number, because it can be changed into a prime (21152683) 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 7 ways as a sum of consecutive naturals, for example, 50396 + ... + 50813.

It is an arithmetic number, because the mean of its divisors is an integer number (3036300).

Almost surely, 2^21152681 is an apocalyptic number.

It is an amenable number.

21152681 is a deficient number, since it is larger than the sum of its proper divisors (3137719).

21152681 is a wasteful number, since it uses less digits than its factorization.

21152681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101239.

The product of its digits is 960, while the sum is 26.

The square root of 21152681 is about 4599.2043877175. The cubic root of 21152681 is about 276.5594311915.

Adding to 21152681 its reverse (18625112), we get a palindrome (39777793).

The spelling of 21152681 in words is "twenty-one million, one hundred fifty-two thousand, six hundred eighty-one".