20722761 has 12 divisors (see below), whose sum is σ = 30017988. Its totient is φ = 13775904.

The previous prime is 20722687. The next prime is 20722769. The reversal of 20722761 is 16722702.

It can be written as a sum of positive squares in 2 ways, for example, as 4076361 + 16646400 = 2019^2 + 4080^2 .

It is not a de Polignac number, because 20722761 - 2¹⁰ = 20721737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20722769) 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 11 ways as a sum of consecutive naturals, for example, 271 + ... + 6443.

It is an arithmetic number, because the mean of its divisors is an integer number (2501499).

Almost surely, 2^20722761 is an apocalyptic number.

It is an amenable number.

20722761 is a deficient number, since it is larger than the sum of its proper divisors (9295227).

20722761 is a wasteful number, since it uses less digits than its factorization.

20722761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6552 (or 6549 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 27.

The square root of 20722761 is about 4552.2259390325. The cubic root of 20722761 is about 274.6729378955.

The spelling of 20722761 in words is "twenty million, seven hundred twenty-two thousand, seven hundred sixty-one".