21307156 has 12 divisors (see below), whose sum is σ = 40155892. Its totient is φ = 9834048.

The previous prime is 21307133. The next prime is 21307183. The reversal of 21307156 is 65170312.

It can be written as a sum of positive squares in 2 ways, for example, as 6330256 + 14976900 = 2516^2 + 3870^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21307156.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 204825 + ... + 204928.

Almost surely, 2^21307156 is an apocalyptic number.

21307156 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21307156 is a deficient number, since it is larger than the sum of its proper divisors (18848736).

21307156 is a wasteful number, since it uses less digits than its factorization.

21307156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409770 (or 409768 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21307156 is about 4615.9675042184. The cubic root of 21307156 is about 277.2310236269.

Adding to 21307156 its reverse (65170312), we get a palindrome (86477468).

The spelling of 21307156 in words is "twenty-one million, three hundred seven thousand, one hundred fifty-six".