20709513 has 30 divisors (see below), whose sum is σ = 34020602. Its totient is φ = 12545280.

The previous prime is 20709511. The next prime is 20709523. The reversal of 20709513 is 31590702.

It can be written as a sum of positive squares in only one way, i.e., 10673289 + 10036224 = 3267^2 + 3168^2 .

It is not a de Polignac number, because 20709513 - 2¹ = 20709511 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20709511) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 8745 + ... + 10857.

Almost surely, 2^20709513 is an apocalyptic number.

It is an amenable number.

20709513 is a deficient number, since it is larger than the sum of its proper divisors (13311089).

20709513 is a wasteful number, since it uses less digits than its factorization.

20709513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2147 (or 2127 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 27.

The square root of 20709513 is about 4550.7705940862. The cubic root of 20709513 is about 274.6143928848.

The spelling of 20709513 in words is "twenty million, seven hundred nine thousand, five hundred thirteen".