21602170661 has 2 divisors, whose sum is σ = 21602170662. Its totient is φ = 21602170660.

The previous prime is 21602170643. The next prime is 21602170679. The reversal of 21602170661 is 16607120612.

It is a balanced prime because it is at equal distance from previous prime (21602170643) and next prime (21602170679).

It can be written as a sum of positive squares in only one way, i.e., 16171954561 + 5430216100 = 127169^2 + 73690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21602170661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21602172661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10801085330 + 10801085331.

It is an arithmetic number, because the mean of its divisors is an integer number (10801085331).

Almost surely, 2^21602170661 is an apocalyptic number.

It is an amenable number.

21602170661 is a deficient number, since it is larger than the sum of its proper divisors (1).

21602170661 is an equidigital number, since it uses as much as digits as its factorization.

21602170661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

It can be divided in two parts, 216021 and 70661, that added together give a palindrome (286682).

The spelling of 21602170661 in words is "twenty-one billion, six hundred two million, one hundred seventy thousand, six hundred sixty-one".