19916261 has 2 divisors, whose sum is σ = 19916262. Its totient is φ = 19916260.

The previous prime is 19916251. The next prime is 19916263. The reversal of 19916261 is 16261991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19088161 + 828100 = 4369^2 + 910^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19916261 is a prime.

Together with 19916263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19916263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9958130 + 9958131.

It is an arithmetic number, because the mean of its divisors is an integer number (9958131).

Almost surely, 2^19916261 is an apocalyptic number.

It is an amenable number.

19916261 is a deficient number, since it is larger than the sum of its proper divisors (1).

19916261 is an equidigital number, since it uses as much as digits as its factorization.

19916261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 35.

The square root of 19916261 is about 4462.7638297360. The cubic root of 19916261 is about 271.0623940067.

The spelling of 19916261 in words is "nineteen million, nine hundred sixteen thousand, two hundred sixty-one".