19933609681 has 2 divisors, whose sum is σ = 19933609682. Its totient is φ = 19933609680.

The previous prime is 19933609651. The next prime is 19933609691. The reversal of 19933609681 is 18690633991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18816980625 + 1116629056 = 137175^2 + 33416^2 .

It is a cyclic number.

It is not a de Polignac number, because 19933609681 - 2²³ = 19925221073 is a prime.

It is a super-2 number, since 2×19933609681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19933609601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9966804840 + 9966804841.

It is an arithmetic number, because the mean of its divisors is an integer number (9966804841).

Almost surely, 2^19933609681 is an apocalyptic number.

It is an amenable number.

19933609681 is a deficient number, since it is larger than the sum of its proper divisors (1).

19933609681 is an equidigital number, since it uses as much as digits as its factorization.

19933609681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1889568, while the sum is 55.

The spelling of 19933609681 in words is "nineteen billion, nine hundred thirty-three million, six hundred nine thousand, six hundred eighty-one".