20861047 has 4 divisors (see below), whose sum is σ = 21534016. Its totient is φ = 20188080.

The previous prime is 20861033. The next prime is 20861051. The reversal of 20861047 is 74016802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74016802 = 2 ⋅37008401.

It is a cyclic number.

It is not a de Polignac number, because 20861047 - 2¹⁵ = 20828279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20861017) 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, 336438 + ... + 336499.

It is an arithmetic number, because the mean of its divisors is an integer number (5383504).

Almost surely, 2^20861047 is an apocalyptic number.

20861047 is a deficient number, since it is larger than the sum of its proper divisors (672969).

20861047 is an equidigital number, since it uses as much as digits as its factorization.

20861047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 672968.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 20861047 is about 4567.3895169998. The cubic root of 20861047 is about 275.2825613606.

Adding to 20861047 its reverse (74016802), we get a palindrome (94877849).

The spelling of 20861047 in words is "twenty million, eight hundred sixty-one thousand, forty-seven".