20709737 has 4 divisors (see below), whose sum is σ = 20730180. Its totient is φ = 20689296.

The previous prime is 20709727. The next prime is 20709769. The reversal of 20709737 is 73790702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7778521 + 12931216 = 2789^2 + 3596^2 .

It is a cyclic number.

It is not a de Polignac number, because 20709737 - 2⁴ = 20709721 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20709697 and 20709706.

It is not an unprimeable number, because it can be changed into a prime (20709727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8618 + ... + 10755.

It is an arithmetic number, because the mean of its divisors is an integer number (5182545).

Almost surely, 2^20709737 is an apocalyptic number.

It is an amenable number.

20709737 is a deficient number, since it is larger than the sum of its proper divisors (20443).

20709737 is a wasteful number, since it uses less digits than its factorization.

20709737 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20442.

The product of its (nonzero) digits is 18522, while the sum is 35.

The square root of 20709737 is about 4550.7952052361. The cubic root of 20709737 is about 274.6153829838.

The spelling of 20709737 in words is "twenty million, seven hundred nine thousand, seven hundred thirty-seven".