20705731 has 4 divisors (see below), whose sum is σ = 20723200. Its totient is φ = 20688264.

The previous prime is 20705701. The next prime is 20705753. The reversal of 20705731 is 13750702.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20705731 is a prime.

It is a super-2 number, since 2×20705731² = 857454592488722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20705696 and 20705705.

It is not an unprimeable number, because it can be changed into a prime (20705701) 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, 6816 + ... + 9373.

It is an arithmetic number, because the mean of its divisors is an integer number (5180800).

Almost surely, 2^20705731 is an apocalyptic number.

20705731 is a deficient number, since it is larger than the sum of its proper divisors (17469).

20705731 is a wasteful number, since it uses less digits than its factorization.

20705731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17468.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 20705731 is about 4550.3550410929. The cubic root of 20705731 is about 274.5976750466.

The spelling of 20705731 in words is "twenty million, seven hundred five thousand, seven hundred thirty-one".