19973221 has 2 divisors, whose sum is σ = 19973222. Its totient is φ = 19973220.

The previous prime is 19973201. The next prime is 19973227. The reversal of 19973221 is 12237991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13653025 + 6320196 = 3695^2 + 2514^2 .

It is a cyclic number.

It is not a de Polignac number, because 19973221 - 2⁵ = 19973189 is a prime.

It is a super-2 number, since 2×19973221² = 797859114229682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19973227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9986610 + 9986611.

It is an arithmetic number, because the mean of its divisors is an integer number (9986611).

Almost surely, 2^19973221 is an apocalyptic number.

It is an amenable number.

19973221 is a deficient number, since it is larger than the sum of its proper divisors (1).

19973221 is an equidigital number, since it uses as much as digits as its factorization.

19973221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 34.

The square root of 19973221 is about 4469.1409689111. The cubic root of 19973221 is about 271.3205585662.

The spelling of 19973221 in words is "nineteen million, nine hundred seventy-three thousand, two hundred twenty-one".