19561957 has 2 divisors, whose sum is σ = 19561958. Its totient is φ = 19561956.

The previous prime is 19561909. The next prime is 19561973. The reversal of 19561957 is 75916591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13003236 + 6558721 = 3606^2 + 2561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19561957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19561757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9780978 + 9780979.

It is an arithmetic number, because the mean of its divisors is an integer number (9780979).

Almost surely, 2^19561957 is an apocalyptic number.

It is an amenable number.

19561957 is a deficient number, since it is larger than the sum of its proper divisors (1).

19561957 is an equidigital number, since it uses as much as digits as its factorization.

19561957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 85050, while the sum is 43.

The square root of 19561957 is about 4422.8901184633. The cubic root of 19561957 is about 269.4453956375.

The spelling of 19561957 in words is "nineteen million, five hundred sixty-one thousand, nine hundred fifty-seven".