21964750981 has 2 divisors, whose sum is σ = 21964750982. Its totient is φ = 21964750980.

The previous prime is 21964750921. The next prime is 21964751033. The reversal of 21964750981 is 18905746912.

It is an a-pointer prime, because the next prime (21964751033) can be obtained adding 21964750981 to its sum of digits (52).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17222362756 + 4742388225 = 131234^2 + 68865^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21964750981 is a prime.

It is a super-2 number, since 2×21964750981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21964750921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10982375490 + 10982375491.

It is an arithmetic number, because the mean of its divisors is an integer number (10982375491).

Almost surely, 2^21964750981 is an apocalyptic number.

It is an amenable number.

21964750981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21964750981 is an equidigital number, since it uses as much as digits as its factorization.

21964750981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1088640, while the sum is 52.

The spelling of 21964750981 in words is "twenty-one billion, nine hundred sixty-four million, seven hundred fifty thousand, nine hundred eighty-one".