20718937 has 4 divisors (see below), whose sum is σ = 21937716. Its totient is φ = 19500160.

The previous prime is 20718931. The next prime is 20718941. The reversal of 20718937 is 73981702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73981702 = 2 ⋅36990851.

It can be written as a sum of positive squares in 2 ways, for example, as 14622976 + 6095961 = 3824^2 + 2469^2 .

It is a cyclic number.

It is not a de Polignac number, because 20718937 - 2⁷ = 20718809 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20718896 and 20718905.

It is not an unprimeable number, because it can be changed into a prime (20718931) 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, 609364 + ... + 609397.

It is an arithmetic number, because the mean of its divisors is an integer number (5484429).

Almost surely, 2^20718937 is an apocalyptic number.

It is an amenable number.

20718937 is a deficient number, since it is larger than the sum of its proper divisors (1218779).

20718937 is a wasteful number, since it uses less digits than its factorization.

20718937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218778.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 20718937 is about 4551.8059053523. The cubic root of 20718937 is about 274.6560415960.

The spelling of 20718937 in words is "twenty million, seven hundred eighteen thousand, nine hundred thirty-seven".