21602538866 has 4 divisors (see below), whose sum is σ = 32403808302. Its totient is φ = 10801269432.

The previous prime is 21602538863. The next prime is 21602538871. The reversal of 21602538866 is 66883520612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20290578025 + 1311960841 = 142445^2 + 36221^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21602538866.

It is not an unprimeable number, because it can be changed into a prime (21602538863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5400634715 + ... + 5400634718.

Almost surely, 2^21602538866 is an apocalyptic number.

21602538866 is a deficient number, since it is larger than the sum of its proper divisors (10801269436).

21602538866 is a wasteful number, since it uses less digits than its factorization.

21602538866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10801269435.

The product of its (nonzero) digits is 829440, while the sum is 47.

The spelling of 21602538866 in words is "twenty-one billion, six hundred two million, five hundred thirty-eight thousand, eight hundred sixty-six".