19729081 has 4 divisors (see below), whose sum is σ = 19740532. Its totient is φ = 19717632.

The previous prime is 19729079. The next prime is 19729097. The reversal of 19729081 is 18092791.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7929856 + 11799225 = 2816^2 + 3435^2 .

It is a cyclic number.

It is not a de Polignac number, because 19729081 - 2¹ = 19729079 is a prime.

It is a super-2 number, since 2×19729081² = 778473274209122, which contains 22 as substring.

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 19729081.

It is not an unprimeable number, because it can be changed into a prime (19729001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2556 + ... + 6781.

It is an arithmetic number, because the mean of its divisors is an integer number (4935133).

Almost surely, 2^19729081 is an apocalyptic number.

It is an amenable number.

19729081 is a deficient number, since it is larger than the sum of its proper divisors (11451).

19729081 is an equidigital number, since it uses as much as digits as its factorization.

19729081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11450.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 19729081 is about 4441.7430137278. The cubic root of 19729081 is about 270.2105399440.

The spelling of 19729081 in words is "nineteen million, seven hundred twenty-nine thousand, eighty-one".