21031156 has 6 divisors (see below), whose sum is σ = 36804530. Its totient is φ = 10515576.

The previous prime is 21031151. The next prime is 21031163. The reversal of 21031156 is 65113012.

It can be written as a sum of positive squares in only one way, i.e., 20976400 + 54756 = 4580^2 + 234^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2628891 + ... + 2628898.

Almost surely, 2^21031156 is an apocalyptic number.

It is an amenable number.

21031156 is a deficient number, since it is larger than the sum of its proper divisors (15773374).

21031156 is a wasteful number, since it uses less digits than its factorization.

21031156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5257793 (or 5257791 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 21031156 is about 4585.9738333314. The cubic root of 21031156 is about 276.0287899674.

Adding to 21031156 its reverse (65113012), we get a palindrome (86144168).

The spelling of 21031156 in words is "twenty-one million, thirty-one thousand, one hundred fifty-six".