191721916 has 12 divisors (see below), whose sum is σ = 341200440. Its totient is φ = 94236080.

The previous prime is 191721911. The next prime is 191721923. The reversal of 191721916 is 619127191.

It is a super-2 number, since 2×191721916² = 73514586149422112, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191721911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 405955 + ... + 406426.

It is an arithmetic number, because the mean of its divisors is an integer number (28433370).

Almost surely, 2^191721916 is an apocalyptic number.

It is an amenable number.

191721916 is a deficient number, since it is larger than the sum of its proper divisors (149478524).

191721916 is a wasteful number, since it uses less digits than its factorization.

191721916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812444 (or 812442 counting only the distinct ones).

The product of its digits is 6804, while the sum is 37.

The square root of 191721916 is about 13846.3683325268. The cubic root of 191721916 is about 576.6211751270.

The spelling of 191721916 in words is "one hundred ninety-one million, seven hundred twenty-one thousand, nine hundred sixteen".