21605661025330 has 32 divisors (see below), whose sum is σ = 39682844290224. Its totient is φ = 8466603565056.

The previous prime is 21605661025313. The next prime is 21605661025349. The reversal of 21605661025330 is 3352016650612.

It can be written as a sum of positive squares in 8 ways, for example, as 16692429695769 + 4913231329561 = 4085637^2 + 2216581^2 .

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 29929639 + ... + 30643018.

Almost surely, 2^{21605661025330} is an apocalyptic number.

21605661025330 is a deficient number, since it is larger than the sum of its proper divisors (18077183264894).

21605661025330 is a wasteful number, since it uses less digits than its factorization.

21605661025330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60573390.

The product of its (nonzero) digits is 194400, while the sum is 40.

Adding to 21605661025330 its reverse (3352016650612), we get a palindrome (24957677675942).

The spelling of 21605661025330 in words is "twenty-one trillion, six hundred five billion, six hundred sixty-one million, twenty-five thousand, three hundred thirty".