20933509 has 4 divisors (see below), whose sum is σ = 20946816. Its totient is φ = 20920204.

The previous prime is 20933503. The next prime is 20933531. The reversal of 20933509 is 90533902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90533902 = 2 ⋅45266951.

It is a cyclic number.

It is not a de Polignac number, because 20933509 - 2⁹ = 20932997 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20933503) 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, 3919 + ... + 7564.

It is an arithmetic number, because the mean of its divisors is an integer number (5236704).

Almost surely, 2^20933509 is an apocalyptic number.

It is an amenable number.

20933509 is a deficient number, since it is larger than the sum of its proper divisors (13307).

20933509 is a wasteful number, since it uses less digits than its factorization.

20933509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13306.

The product of its (nonzero) digits is 7290, while the sum is 31.

The square root of 20933509 is about 4575.3151804001. The cubic root of 20933509 is about 275.6009294200.

The spelling of 20933509 in words is "twenty million, nine hundred thirty-three thousand, five hundred nine".