1221954102157 has 2 divisors, whose sum is σ = 1221954102158. Its totient is φ = 1221954102156.

The previous prime is 1221954102151. The next prime is 1221954102203. The reversal of 1221954102157 is 7512014591221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1034331714441 + 187622387716 = 1017021^2 + 433154^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221954102157 - 2³⁹ = 672198288269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221954102151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610977051078 + 610977051079.

It is an arithmetic number, because the mean of its divisors is an integer number (610977051079).

Almost surely, 2^{1221954102157} is an apocalyptic number.

It is an amenable number.

1221954102157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221954102157 is an equidigital number, since it uses as much as digits as its factorization.

1221954102157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50400, while the sum is 40.

Adding to 1221954102157 its reverse (7512014591221), we get a palindrome (8733968693378).

The spelling of 1221954102157 in words is "one trillion, two hundred twenty-one billion, nine hundred fifty-four million, one hundred two thousand, one hundred fifty-seven".