20857145 has 4 divisors (see below), whose sum is σ = 25028580. Its totient is φ = 16685712.

The previous prime is 20857103. The next prime is 20857157. The reversal of 20857145 is 54175802.

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 5112121 + 15745024 = 2261^2 + 3968^2 .

It is a cyclic number.

It is not a de Polignac number, because 20857145 - 2¹⁴ = 20840761 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2085710 + ... + 2085719.

It is an arithmetic number, because the mean of its divisors is an integer number (6257145).

Almost surely, 2^20857145 is an apocalyptic number.

It is an amenable number.

20857145 is a deficient number, since it is larger than the sum of its proper divisors (4171435).

20857145 is an equidigital number, since it uses as much as digits as its factorization.

20857145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4171434.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 20857145 is about 4566.9623383601. The cubic root of 20857145 is about 275.2653966814.

The spelling of 20857145 in words is "twenty million, eight hundred fifty-seven thousand, one hundred forty-five".