21052761 has 8 divisors (see below), whose sum is σ = 28197120. Its totient is φ = 13971792.

The previous prime is 21052739. The next prime is 21052769. The reversal of 21052761 is 16725012.

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

It is not a de Polignac number, because 21052761 - 2⁵ = 21052729 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21052769) 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, 15066 + ... + 16403.

It is an arithmetic number, because the mean of its divisors is an integer number (3524640).

Almost surely, 2^21052761 is an apocalyptic number.

It is an amenable number.

21052761 is a deficient number, since it is larger than the sum of its proper divisors (7144359).

21052761 is a wasteful number, since it uses less digits than its factorization.

21052761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31695.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21052761 is about 4588.3287807218. The cubic root of 21052761 is about 276.1232777370.

Adding to 21052761 its reverse (16725012), we get a palindrome (37777773).

The spelling of 21052761 in words is "twenty-one million, fifty-two thousand, seven hundred sixty-one".