21612755551217 has 8 divisors (see below), whose sum is σ = 22020805331496. Its totient is φ = 21204715472512.

The previous prime is 21612755551181. The next prime is 21612755551243. The reversal of 21612755551217 is 71215555721612.

It can be written as a sum of positive squares in 4 ways, for example, as 1697207067361 + 19915548483856 = 1302769^2 + 4462684^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21612755551217 - 2¹² = 21612755547121 is a prime.

It is a super-2 number, since 2×21612755551217² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21612755571217) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2153003 + ... + 6918159.

It is an arithmetic number, because the mean of its divisors is an integer number (2752600666437).

Almost surely, 2^{21612755551217} is an apocalyptic number.

It is an amenable number.

21612755551217 is a deficient number, since it is larger than the sum of its proper divisors (408049780279).

21612755551217 is an equidigital number, since it uses as much as digits as its factorization.

21612755551217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4850787.

The product of its digits is 1470000, while the sum is 50.

The spelling of 21612755551217 in words is "twenty-one trillion, six hundred twelve billion, seven hundred fifty-five million, five hundred fifty-one thousand, two hundred seventeen".