19921097 has 10 divisors (see below), whose sum is σ = 23242698. Its totient is φ = 17073168.

The previous prime is 19921067. The next prime is 19921129. The reversal of 19921097 is 79012991.

It can be written as a sum of positive squares in only one way, i.e., 19882681 + 38416 = 4459^2 + 196^2 .

It is not a de Polignac number, because 19921097 - 2¹⁴ = 19904713 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19921097.

It is not an unprimeable number, because it can be changed into a prime (19921037) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1748 + ... + 6549.

Almost surely, 2^19921097 is an apocalyptic number.

It is an amenable number.

19921097 is a deficient number, since it is larger than the sum of its proper divisors (3321601).

19921097 is an frugal number, since it uses more digits than its factorization.

19921097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8325 (or 8304 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 38.

The square root of 19921097 is about 4463.3056135559. The cubic root of 19921097 is about 271.0843317197.

The spelling of 19921097 in words is "nineteen million, nine hundred twenty-one thousand, ninety-seven".