21131440061 has 2 divisors, whose sum is σ = 21131440062. Its totient is φ = 21131440060.

The previous prime is 21131440039. The next prime is 21131440069. The reversal of 21131440061 is 16004413112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16956987961 + 4174452100 = 130219^2 + 64610^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131440061 - 2³⁴ = 3951570877 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131440069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565720030 + 10565720031.

It is an arithmetic number, because the mean of its divisors is an integer number (10565720031).

Almost surely, 2^21131440061 is an apocalyptic number.

It is an amenable number.

21131440061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131440061 is an equidigital number, since it uses as much as digits as its factorization.

21131440061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 21131440061 its reverse (16004413112), we get a palindrome (37135853173).

The spelling of 21131440061 in words is "twenty-one billion, one hundred thirty-one million, four hundred forty thousand, sixty-one".