21663653026 has 4 divisors (see below), whose sum is σ = 32495479542. Its totient is φ = 10831826512.

The previous prime is 21663653023. The next prime is 21663653101. The reversal of 21663653026 is 62035636612.

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., 17438523025 + 4225130001 = 132055^2 + 65001^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21663653026.

It is not an unprimeable number, because it can be changed into a prime (21663653023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5415913255 + ... + 5415913258.

Almost surely, 2^21663653026 is an apocalyptic number.

21663653026 is a deficient number, since it is larger than the sum of its proper divisors (10831826516).

21663653026 is a wasteful number, since it uses less digits than its factorization.

21663653026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10831826515.

The product of its (nonzero) digits is 233280, while the sum is 40.

The spelling of 21663653026 in words is "twenty-one billion, six hundred sixty-three million, six hundred fifty-three thousand, twenty-six".