19725121 has 4 divisors (see below), whose sum is σ = 21242452. Its totient is φ = 18207792.

The previous prime is 19725109. The next prime is 19725161. The reversal of 19725121 is 12152791.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5953600 + 13771521 = 2440^2 + 3711^2 .

It is a cyclic number.

It is not a de Polignac number, because 19725121 - 2⁷ = 19724993 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 19725121.

It is not an unprimeable number, because it can be changed into a prime (19725161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 758646 + ... + 758671.

It is an arithmetic number, because the mean of its divisors is an integer number (5310613).

Almost surely, 2^19725121 is an apocalyptic number.

It is an amenable number.

19725121 is a deficient number, since it is larger than the sum of its proper divisors (1517331).

19725121 is a wasteful number, since it uses less digits than its factorization.

19725121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1517330.

The product of its digits is 1260, while the sum is 28.

The square root of 19725121 is about 4441.2972204076. The cubic root of 19725121 is about 270.1924599442.

The spelling of 19725121 in words is "nineteen million, seven hundred twenty-five thousand, one hundred twenty-one".