197913721 has 2 divisors, whose sum is σ = 197913722. Its totient is φ = 197913720.

The previous prime is 197913679. The next prime is 197913733. The reversal of 197913721 is 127319791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 103124025 + 94789696 = 10155^2 + 9736^2 .

It is an emirp because it is prime and its reverse (127319791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 197913721 - 2¹¹ = 197911673 is a prime.

It is equal to p_10969726 and since 197913721 and 10969726 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (197913761) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98956860 + 98956861.

It is an arithmetic number, because the mean of its divisors is an integer number (98956861).

Almost surely, 2^197913721 is an apocalyptic number.

It is an amenable number.

197913721 is a deficient number, since it is larger than the sum of its proper divisors (1).

197913721 is an equidigital number, since it uses as much as digits as its factorization.

197913721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23814, while the sum is 40.

The square root of 197913721 is about 14068.1811546482. The cubic root of 197913721 is about 582.7629969109.

The spelling of 197913721 in words is "one hundred ninety-seven million, nine hundred thirteen thousand, seven hundred twenty-one".