10000000021981 has 2 divisors, whose sum is σ = 10000000021982. Its totient is φ = 10000000021980.

The previous prime is 10000000021969. The next prime is 10000000022039. The reversal of 10000000021981 is 18912000000001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9378851125081 + 621148896900 = 3062491^2 + 788130^2 .

It is an emirp because it is prime and its reverse (18912000000001) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 10000000021981 - 2⁷ = 10000000021853 is a prime.

It is a super-2 number, since 2×10000000021981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (10000000021481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5000000010990 + 5000000010991.

It is an arithmetic number, because the mean of its divisors is an integer number (5000000010991).

Almost surely, 2^{10000000021981} is an apocalyptic number.

It is an amenable number.

10000000021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

10000000021981 is an equidigital number, since it uses as much as digits as its factorization.

10000000021981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 22.

Adding to 10000000021981 its reverse (18912000000001), we get a palindrome (28912000021982).

The spelling of 10000000021981 in words is "ten trillion, twenty-one thousand, nine hundred eighty-one".