1221528251221 has 32 divisors (see below), whose sum is σ = 1338713671680. Its totient is φ = 1109974272000.

The previous prime is 1221528251219. The next prime is 1221528251227.

1221528251221 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 1221528251221 - 2¹ = 1221528251219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221528251227) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 222944560 + ... + 222950038.

It is an arithmetic number, because the mean of its divisors is an integer number (41834802240).

Almost surely, 2^{1221528251221} is an apocalyptic number.

It is an amenable number.

1221528251221 is a deficient number, since it is larger than the sum of its proper divisors (117185420459).

1221528251221 is a wasteful number, since it uses less digits than its factorization.

1221528251221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8805.

The product of its digits is 12800, while the sum is 34.

The spelling of 1221528251221 in words is "one trillion, two hundred twenty-one billion, five hundred twenty-eight million, two hundred fifty-one thousand, two hundred twenty-one".