20916157 has 4 divisors (see below), whose sum is σ = 21151260. Its totient is φ = 20681056.

The previous prime is 20916151. The next prime is 20916197. The reversal of 20916157 is 75161902.

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 5635876 + 15280281 = 2374^2 + 3909^2 .

It is a cyclic number.

It is not a de Polignac number, because 20916157 - 2⁷ = 20916029 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20916151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117418 + ... + 117595.

It is an arithmetic number, because the mean of its divisors is an integer number (5287815).

Almost surely, 2^20916157 is an apocalyptic number.

It is an amenable number.

20916157 is a deficient number, since it is larger than the sum of its proper divisors (235103).

20916157 is an equidigital number, since it uses as much as digits as its factorization.

20916157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235102.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 20916157 is about 4573.4185244738. The cubic root of 20916157 is about 275.5247588923.

The spelling of 20916157 in words is "twenty million, nine hundred sixteen thousand, one hundred fifty-seven".