20937421 has 4 divisors (see below), whose sum is σ = 22169052. Its totient is φ = 19705792.

The previous prime is 20937409. The next prime is 20937437. The reversal of 20937421 is 12473902.

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 11634921 + 9302500 = 3411^2 + 3050^2 .

It is a cyclic number.

It is not a de Polignac number, because 20937421 - 2¹¹ = 20935373 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 20937421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20937481) 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, 615790 + ... + 615823.

It is an arithmetic number, because the mean of its divisors is an integer number (5542263).

Almost surely, 2^20937421 is an apocalyptic number.

It is an amenable number.

20937421 is a deficient number, since it is larger than the sum of its proper divisors (1231631).

20937421 is a wasteful number, since it uses less digits than its factorization.

20937421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1231630.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 20937421 is about 4575.7426719605. The cubic root of 20937421 is about 275.6180962135.

The spelling of 20937421 in words is "twenty million, nine hundred thirty-seven thousand, four hundred twenty-one".