19621009 has 4 divisors (see below), whose sum is σ = 20775204. Its totient is φ = 18466816.

The previous prime is 19620983. The next prime is 19621027. The reversal of 19621009 is 90012691.

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 11937025 + 7683984 = 3455^2 + 2772^2 .

It is a cyclic number.

It is not a de Polignac number, because 19621009 - 2¹¹ = 19618961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19621039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 577072 + ... + 577105.

It is an arithmetic number, because the mean of its divisors is an integer number (5193801).

Almost surely, 2^19621009 is an apocalyptic number.

It is an amenable number.

19621009 is a deficient number, since it is larger than the sum of its proper divisors (1154195).

19621009 is a wasteful number, since it uses less digits than its factorization.

19621009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1154194.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 19621009 is about 4429.5608134442. The cubic root of 19621009 is about 269.7162496859.

The spelling of 19621009 in words is "nineteen million, six hundred twenty-one thousand, nine".