20512157 has 4 divisors (see below), whose sum is σ = 20585436. Its totient is φ = 20438880.

The previous prime is 20512139. The next prime is 20512169. The reversal of 20512157 is 75121502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75121502 = 2 ⋅37560751.

It can be written as a sum of positive squares in 2 ways, for example, as 10201636 + 10310521 = 3194^2 + 3211^2 .

It is a cyclic number.

It is not a de Polignac number, because 20512157 - 2¹⁴ = 20495773 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 (20512357) 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, 36218 + ... + 36779.

It is an arithmetic number, because the mean of its divisors is an integer number (5146359).

Almost surely, 2^20512157 is an apocalyptic number.

It is an amenable number.

20512157 is a deficient number, since it is larger than the sum of its proper divisors (73279).

20512157 is an equidigital number, since it uses as much as digits as its factorization.

20512157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73278.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 20512157 is about 4529.0348861540. The cubic root of 20512157 is about 273.7392737122.

Adding to 20512157 its reverse (75121502), we get a palindrome (95633659).

The spelling of 20512157 in words is "twenty million, five hundred twelve thousand, one hundred fifty-seven".