19721361 has 32 divisors (see below), whose sum is σ = 29748096. Its totient is φ = 11520000.

The previous prime is 19721293. The next prime is 19721371. The reversal of 19721361 is 16312791.

It is not a de Polignac number, because 19721361 - 2¹⁴ = 19704977 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (19721371) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 195211 + ... + 195311.

It is an arithmetic number, because the mean of its divisors is an integer number (929628).

Almost surely, 2^19721361 is an apocalyptic number.

19721361 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19721361 is a deficient number, since it is larger than the sum of its proper divisors (10026735).

19721361 is a wasteful number, since it uses less digits than its factorization.

19721361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273.

The product of its digits is 2268, while the sum is 30.

The square root of 19721361 is about 4440.8739004840. The cubic root of 19721361 is about 270.1752908360.

It can be divided in two parts, 1972 and 1361, that added together give a palindrome (3333).

The spelling of 19721361 in words is "nineteen million, seven hundred twenty-one thousand, three hundred sixty-one".