19915957 has 2 divisors, whose sum is σ = 19915958. Its totient is φ = 19915956.

The previous prime is 19915949. The next prime is 19915963. The reversal of 19915957 is 75951991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19838116 + 77841 = 4454^2 + 279^2 .

It is an emirp because it is prime and its reverse (75951991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19915957 - 2³ = 19915949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19915967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9957978 + 9957979.

It is an arithmetic number, because the mean of its divisors is an integer number (9957979).

Almost surely, 2^19915957 is an apocalyptic number.

It is an amenable number.

19915957 is a deficient number, since it is larger than the sum of its proper divisors (1).

19915957 is an equidigital number, since it uses as much as digits as its factorization.

19915957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127575, while the sum is 46.

The square root of 19915957 is about 4462.7297699950. The cubic root of 19915957 is about 271.0610148424.

The spelling of 19915957 in words is "nineteen million, nine hundred fifteen thousand, nine hundred fifty-seven".