20861573 has 4 divisors (see below), whose sum is σ = 21203628. Its totient is φ = 20519520.

The previous prime is 20861557. The next prime is 20861587. The reversal of 20861573 is 37516802.

It is a happy number.

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 1085764 + 19775809 = 1042^2 + 4447^2 .

It is a cyclic number.

It is not a de Polignac number, because 20861573 - 2⁴ = 20861557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20861173) 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, 170936 + ... + 171057.

It is an arithmetic number, because the mean of its divisors is an integer number (5300907).

Almost surely, 2^20861573 is an apocalyptic number.

It is an amenable number.

20861573 is a deficient number, since it is larger than the sum of its proper divisors (342055).

20861573 is an equidigital number, since it uses as much as digits as its factorization.

20861573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342054.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20861573 is about 4567.4470987632. The cubic root of 20861573 is about 275.2848750413.

The spelling of 20861573 in words is "twenty million, eight hundred sixty-one thousand, five hundred seventy-three".