21899956061 has 2 divisors, whose sum is σ = 21899956062. Its totient is φ = 21899956060.

The previous prime is 21899956049. The next prime is 21899956103. The reversal of 21899956061 is 16065999812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20802292900 + 1097663161 = 144230^2 + 33131^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21899956061 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21899955988 and 21899956006.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21899956031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10949978030 + 10949978031.

It is an arithmetic number, because the mean of its divisors is an integer number (10949978031).

Almost surely, 2^21899956061 is an apocalyptic number.

It is an amenable number.

21899956061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21899956061 is an equidigital number, since it uses as much as digits as its factorization.

21899956061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2099520, while the sum is 56.

The spelling of 21899956061 in words is "twenty-one billion, eight hundred ninety-nine million, nine hundred fifty-six thousand, sixty-one".