20720737 has 4 divisors (see below), whose sum is σ = 20760880. Its totient is φ = 20680596.

The previous prime is 20720731. The next prime is 20720743. The reversal of 20720737 is 73702702.

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 an interprime number because it is at equal distance from previous prime (20720731) and next prime (20720743).

It is a cyclic number.

It is not a de Polignac number, because 20720737 - 2¹¹ = 20718689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20720731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19287 + ... + 20332.

It is an arithmetic number, because the mean of its divisors is an integer number (5190220).

Almost surely, 2^20720737 is an apocalyptic number.

It is an amenable number.

20720737 is a deficient number, since it is larger than the sum of its proper divisors (40143).

20720737 is an equidigital number, since it uses as much as digits as its factorization.

20720737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40142.

The product of its (nonzero) digits is 4116, while the sum is 28.

The square root of 20720737 is about 4552.0036247789. The cubic root of 20720737 is about 274.6639951340.

The spelling of 20720737 in words is "twenty million, seven hundred twenty thousand, seven hundred thirty-seven".