20938521 has 4 divisors (see below), whose sum is σ = 27918032. Its totient is φ = 13959012.

The previous prime is 20938507. The next prime is 20938529. The reversal of 20938521 is 12583902.

It is a happy number.

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 not a de Polignac number, because 20938521 - 2²³ = 12549913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20938529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3489751 + ... + 3489756.

It is an arithmetic number, because the mean of its divisors is an integer number (6979508).

Almost surely, 2^20938521 is an apocalyptic number.

It is an amenable number.

20938521 is a deficient number, since it is larger than the sum of its proper divisors (6979511).

20938521 is an equidigital number, since it uses as much as digits as its factorization.

20938521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6979510.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 20938521 is about 4575.8628694488. The cubic root of 20938521 is about 275.6229228920.

The spelling of 20938521 in words is "twenty million, nine hundred thirty-eight thousand, five hundred twenty-one".