20506837 has 4 divisors (see below), whose sum is σ = 22084300. Its totient is φ = 18929376.

The previous prime is 20506831. The next prime is 20506861. The reversal of 20506837 is 73860502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73860502 = 2 ⋅36930251.

It can be written as a sum of positive squares in 2 ways, for example, as 11350161 + 9156676 = 3369^2 + 3026^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20506837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20506799 and 20506808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20506831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 788712 + ... + 788737.

It is an arithmetic number, because the mean of its divisors is an integer number (5521075).

Almost surely, 2^20506837 is an apocalyptic number.

It is an amenable number.

20506837 is a deficient number, since it is larger than the sum of its proper divisors (1577463).

20506837 is a wasteful number, since it uses less digits than its factorization.

20506837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1577462.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 20506837 is about 4528.4475264709. The cubic root of 20506837 is about 273.7156061402.

The spelling of 20506837 in words is "twenty million, five hundred six thousand, eight hundred thirty-seven".