21602754221 has 2 divisors, whose sum is σ = 21602754222. Its totient is φ = 21602754220.

The previous prime is 21602754203. The next prime is 21602754253. The reversal of 21602754221 is 12245720612.

It is an a-pointer prime, because the next prime (21602754253) can be obtained adding 21602754221 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21559048900 + 43705321 = 146830^2 + 6611^2 .

It is a cyclic number.

It is not a de Polignac number, because 21602754221 - 2⁶ = 21602754157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21604754221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10801377110 + 10801377111.

It is an arithmetic number, because the mean of its divisors is an integer number (10801377111).

Almost surely, 2^21602754221 is an apocalyptic number.

It is an amenable number.

21602754221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21602754221 is an equidigital number, since it uses as much as digits as its factorization.

21602754221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13440, while the sum is 32.

The spelling of 21602754221 in words is "twenty-one billion, six hundred two million, seven hundred fifty-four thousand, two hundred twenty-one".