20671156 has 18 divisors (see below), whose sum is σ = 39763010. Its totient is φ = 9395760.

The previous prime is 20671151. The next prime is 20671159. The reversal of 20671156 is 65117602.

It can be written as a sum of positive squares in only one way, i.e., 15335056 + 5336100 = 3916^2 + 2310^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20671151) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 20871 + ... + 21838.

Almost surely, 2^20671156 is an apocalyptic number.

It is an amenable number.

20671156 is a deficient number, since it is larger than the sum of its proper divisors (19091854).

20671156 is a wasteful number, since it uses less digits than its factorization.

20671156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42735 (or 42722 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 20671156 is about 4546.5542996867. The cubic root of 20671156 is about 274.4447463061. Note that the first 3 decimals are identical.

Adding to 20671156 its reverse (65117602), we get a palindrome (85788758).

It can be divided in two parts, 2067115 and 6, that multiplied together give a triangular number (12402690 = T₄₉₈₀).

The spelling of 20671156 in words is "twenty million, six hundred seventy-one thousand, one hundred fifty-six".