20507621 has 4 divisors (see below), whose sum is σ = 20528544. Its totient is φ = 20486700.

The previous prime is 20507581. The next prime is 20507623. The reversal of 20507621 is 12670502.

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.

It is a cyclic number.

It is not a de Polignac number, because 20507621 - 2¹⁰ = 20506597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20507623) 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, 8915 + ... + 10976.

It is an arithmetic number, because the mean of its divisors is an integer number (5132136).

Almost surely, 2^20507621 is an apocalyptic number.

It is an amenable number.

20507621 is a deficient number, since it is larger than the sum of its proper divisors (20923).

20507621 is a wasteful number, since it uses less digits than its factorization.

20507621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20922.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20507621 is about 4528.5340895261. The cubic root of 20507621 is about 273.7190942501.

The spelling of 20507621 in words is "twenty million, five hundred seven thousand, six hundred twenty-one".