21256036 has 6 divisors (see below), whose sum is σ = 37198070. Its totient is φ = 10628016.

The previous prime is 21256033. The next prime is 21256057. The reversal of 21256036 is 63065212.

It can be written as a sum of positive squares in only one way, i.e., 20702500 + 553536 = 4550^2 + 744^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21256036.

It is not an unprimeable number, because it can be changed into a prime (21256033) 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, 2657001 + ... + 2657008.

Almost surely, 2^21256036 is an apocalyptic number.

It is an amenable number.

21256036 is a deficient number, since it is larger than the sum of its proper divisors (15942034).

21256036 is a wasteful number, since it uses less digits than its factorization.

21256036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5314013 (or 5314011 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 21256036 is about 4610.4268782836. The cubic root of 21256036 is about 277.0091357489.

The spelling of 21256036 in words is "twenty-one million, two hundred fifty-six thousand, thirty-six".