20861705 has 4 divisors (see below), whose sum is σ = 25034052. Its totient is φ = 16689360.

The previous prime is 20861699. The next prime is 20861741. The reversal of 20861705 is 50716802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50716802 = 2 ⋅25358401.

It can be written as a sum of positive squares in 2 ways, for example, as 3087049 + 17774656 = 1757^2 + 4216^2 .

It is not a de Polignac number, because 20861705 - 2¹² = 20857609 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2086166 + ... + 2086175.

It is an arithmetic number, because the mean of its divisors is an integer number (6258513).

Almost surely, 2^20861705 is an apocalyptic number.

It is an amenable number.

20861705 is a deficient number, since it is larger than the sum of its proper divisors (4172347).

20861705 is an equidigital number, since it uses as much as digits as its factorization.

20861705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4172346.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 20861705 is about 4567.4615488256. The cubic root of 20861705 is about 275.2854556548.

The spelling of 20861705 in words is "twenty million, eight hundred sixty-one thousand, seven hundred five".