20787157 has 2 divisors, whose sum is σ = 20787158. Its totient is φ = 20787156.

The previous prime is 20787149. The next prime is 20787187. The reversal of 20787157 is 75178702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15729156 + 5058001 = 3966^2 + 2249^2 .

It is a cyclic number.

It is not a de Polignac number, because 20787157 - 2³ = 20787149 is a prime.

It is a super-2 number, since 2×20787157² = 864211792285298, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20787127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393578 + 10393579.

It is an arithmetic number, because the mean of its divisors is an integer number (10393579).

Almost surely, 2^20787157 is an apocalyptic number.

It is an amenable number.

20787157 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787157 is an equidigital number, since it uses as much as digits as its factorization.

20787157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27440, while the sum is 37.

The square root of 20787157 is about 4559.2934759675. The cubic root of 20787157 is about 274.9571591666.

The spelling of 20787157 in words is "twenty million, seven hundred eighty-seven thousand, one hundred fifty-seven".