21532681 has 8 divisors (see below), whose sum is σ = 23094720. Its totient is φ = 20013552.

The previous prime is 21532663. The next prime is 21532697. The reversal of 21532681 is 18623512.

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 21532681 - 2⁹ = 21532169 is a prime.

It is a super-2 number, since 2×21532681² = 927312702095522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21532781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9685 + ... + 11698.

It is an arithmetic number, because the mean of its divisors is an integer number (2886840).

Almost surely, 2^21532681 is an apocalyptic number.

It is an amenable number.

21532681 is a deficient number, since it is larger than the sum of its proper divisors (1562039).

21532681 is a wasteful number, since it uses less digits than its factorization.

21532681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21455.

The product of its digits is 2880, while the sum is 28.

The square root of 21532681 is about 4640.3319924333. The cubic root of 21532681 is about 278.2057075207.

It can be divided in two parts, 215 and 32681, that added together give a triangular number (32896 = T₂₅₆).

The spelling of 21532681 in words is "twenty-one million, five hundred thirty-two thousand, six hundred eighty-one".