20646826261 has 4 divisors (see below), whose sum is σ = 20649061132. Its totient is φ = 20644591392.

The previous prime is 20646826259. The next prime is 20646826271. The reversal of 20646826261 is 16262864602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16262864602 = 2 ⋅8131432301.

It can be written as a sum of positive squares in 2 ways, for example, as 18940640625 + 1706185636 = 137625^2 + 41306^2 .

It is a cyclic number.

It is not a de Polignac number, because 20646826261 - 2¹ = 20646826259 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 (20646826201) 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, 1103520 + ... + 1122073.

It is an arithmetic number, because the mean of its divisors is an integer number (5162265283).

Almost surely, 2^20646826261 is an apocalyptic number.

It is an amenable number.

20646826261 is a deficient number, since it is larger than the sum of its proper divisors (2234871).

20646826261 is an equidigital number, since it uses as much as digits as its factorization.

20646826261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2234870.

The product of its (nonzero) digits is 331776, while the sum is 43.

The spelling of 20646826261 in words is "twenty billion, six hundred forty-six million, eight hundred twenty-six thousand, two hundred sixty-one".