20911573 has 4 divisors (see below), whose sum is σ = 21036960. Its totient is φ = 20786188.

The previous prime is 20911567. The next prime is 20911589. The reversal of 20911573 is 37511902.

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, and also an emirpimes, since its reverse is a distinct semiprime: 37511902 = 2 ⋅18755951.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20911573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20911073) 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, 62443 + ... + 62776.

It is an arithmetic number, because the mean of its divisors is an integer number (5259240).

Almost surely, 2^20911573 is an apocalyptic number.

It is an amenable number.

20911573 is a deficient number, since it is larger than the sum of its proper divisors (125387).

20911573 is a wasteful number, since it uses less digits than its factorization.

20911573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125386.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 20911573 is about 4572.9173401670. The cubic root of 20911573 is about 275.5046293536.

The spelling of 20911573 in words is "twenty million, nine hundred eleven thousand, five hundred seventy-three".