19801961 has 2 divisors, whose sum is σ = 19801962. Its totient is φ = 19801960.

The previous prime is 19801949. The next prime is 19801997. The reversal of 19801961 is 16910891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17682025 + 2119936 = 4205^2 + 1456^2 .

It is an emirp because it is prime and its reverse (16910891) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19801961 is a prime.

It is not a weakly prime, because it can be changed into another prime (19801931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9900980 + 9900981.

It is an arithmetic number, because the mean of its divisors is an integer number (9900981).

Almost surely, 2^19801961 is an apocalyptic number.

It is an amenable number.

19801961 is a deficient number, since it is larger than the sum of its proper divisors (1).

19801961 is an equidigital number, since it uses as much as digits as its factorization.

19801961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 35.

The square root of 19801961 is about 4449.9394377901. The cubic root of 19801961 is about 270.5428538677.

The spelling of 19801961 in words is "nineteen million, eight hundred one thousand, nine hundred sixty-one".