20720501 has 4 divisors (see below), whose sum is σ = 21939372. Its totient is φ = 19501632.

The previous prime is 20720459. The next prime is 20720519. The reversal of 20720501 is 10502702.

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 6507601 + 14212900 = 2551^2 + 3770^2 .

It is a cyclic number.

It is not a de Polignac number, because 20720501 - 2⁶ = 20720437 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1218853 = 20720501 / (2 + 0 + 7 + 2 + 0 + 5 + 0 + 1).

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 20720501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20720521) 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, 609410 + ... + 609443.

It is an arithmetic number, because the mean of its divisors is an integer number (5484843).

Almost surely, 2^20720501 is an apocalyptic number.

It is an amenable number.

20720501 is a deficient number, since it is larger than the sum of its proper divisors (1218871).

20720501 is a wasteful number, since it uses less digits than its factorization.

20720501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218870.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 20720501 is about 4551.9777020543. The cubic root of 20720501 is about 274.6629523631.

The spelling of 20720501 in words is "twenty million, seven hundred twenty thousand, five hundred one".