20001251861 has 2 divisors, whose sum is σ = 20001251862. Its totient is φ = 20001251860.

The previous prime is 20001251857. The next prime is 20001251887. The reversal of 20001251861 is 16815210002.

It is an a-pointer prime, because the next prime (20001251887) can be obtained adding 20001251861 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19183635025 + 817616836 = 138505^2 + 28594^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001251861 - 2² = 20001251857 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20001251861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20001251891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000625930 + 10000625931.

It is an arithmetic number, because the mean of its divisors is an integer number (10000625931).

Almost surely, 2^20001251861 is an apocalyptic number.

It is an amenable number.

20001251861 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001251861 is an equidigital number, since it uses as much as digits as its factorization.

20001251861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 26.

Adding to 20001251861 its reverse (16815210002), we get a palindrome (36816461863).

The spelling of 20001251861 in words is "twenty billion, one million, two hundred fifty-one thousand, eight hundred sixty-one".