20809577 has 4 divisors (see below), whose sum is σ = 21372036. Its totient is φ = 20247120.

The previous prime is 20809573. The next prime is 20809583. The reversal of 20809577 is 77590802.

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 19219456 + 1590121 = 4384^2 + 1261^2 .

It is a cyclic number.

It is not a de Polignac number, because 20809577 - 2² = 20809573 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 20809577.

It is not an unprimeable number, because it can be changed into a prime (20809573) 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, 281174 + ... + 281247.

It is an arithmetic number, because the mean of its divisors is an integer number (5343009).

Almost surely, 2^20809577 is an apocalyptic number.

It is an amenable number.

20809577 is a deficient number, since it is larger than the sum of its proper divisors (562459).

20809577 is an equidigital number, since it uses as much as digits as its factorization.

20809577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562458.

The product of its (nonzero) digits is 35280, while the sum is 38.

The square root of 20809577 is about 4561.7515276481. The cubic root of 20809577 is about 275.0559753825.

The spelling of 20809577 in words is "twenty million, eight hundred nine thousand, five hundred seventy-seven".