20612261209 has 2 divisors, whose sum is σ = 20612261210. Its totient is φ = 20612261208.

The previous prime is 20612261179. The next prime is 20612261237. The reversal of 20612261209 is 90216221602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20562699609 + 49561600 = 143397^2 + 7040^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20612261209 is a prime.

It is a super-2 number, since 2×20612261209² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20612265209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10306130604 + 10306130605.

It is an arithmetic number, because the mean of its divisors is an integer number (10306130605).

Almost surely, 2^20612261209 is an apocalyptic number.

It is an amenable number.

20612261209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20612261209 is an equidigital number, since it uses as much as digits as its factorization.

20612261209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 31.

The spelling of 20612261209 in words is "twenty billion, six hundred twelve million, two hundred sixty-one thousand, two hundred nine".