19915961 has 4 divisors (see below), whose sum is σ = 21447972. Its totient is φ = 18383952.

The previous prime is 19915957. The next prime is 19915963. The reversal of 19915961 is 16951991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3763600 + 16152361 = 1940^2 + 4019^2 .

It is a cyclic number.

It is not a de Polignac number, because 19915961 - 2² = 19915957 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19915963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 765986 + ... + 766011.

It is an arithmetic number, because the mean of its divisors is an integer number (5361993).

Almost surely, 2^19915961 is an apocalyptic number.

It is an amenable number.

19915961 is a deficient number, since it is larger than the sum of its proper divisors (1532011).

19915961 is a wasteful number, since it uses less digits than its factorization.

19915961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1532010.

The product of its digits is 21870, while the sum is 41.

The square root of 19915961 is about 4462.7302181512. The cubic root of 19915961 is about 271.0610329894.

The spelling of 19915961 in words is "nineteen million, nine hundred fifteen thousand, nine hundred sixty-one".