1221011948857 has 2 divisors, whose sum is σ = 1221011948858. Its totient is φ = 1221011948856.

The previous prime is 1221011948791. The next prime is 1221011948911. The reversal of 1221011948857 is 7588491101221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1144138286736 + 76873662121 = 1069644^2 + 277261^2 .

It is an emirp because it is prime and its reverse (7588491101221) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221011948857 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221011948857.

It is not a weakly prime, because it can be changed into another prime (1221011948357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610505974428 + 610505974429.

It is an arithmetic number, because the mean of its divisors is an integer number (610505974429).

Almost surely, 2^{1221011948857} is an apocalyptic number.

It is an amenable number.

1221011948857 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221011948857 is an equidigital number, since it uses as much as digits as its factorization.

1221011948857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 322560, while the sum is 49.

The spelling of 1221011948857 in words is "one trillion, two hundred twenty-one billion, eleven million, nine hundred forty-eight thousand, eight hundred fifty-seven".