1221021522521 has 16 divisors (see below), whose sum is σ = 1289743076160. Its totient is φ = 1152747288000.

The previous prime is 1221021522517. The next prime is 1221021522551. The reversal of 1221021522521 is 1252251201221.

It is a cyclic number.

It is not a de Polignac number, because 1221021522521 - 2² = 1221021522517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221021522551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31694771 + ... + 31733271.

It is an arithmetic number, because the mean of its divisors is an integer number (80608942260).

Almost surely, 2^{1221021522521} is an apocalyptic number.

It is an amenable number.

1221021522521 is a deficient number, since it is larger than the sum of its proper divisors (68721553639).

1221021522521 is a wasteful number, since it uses less digits than its factorization.

1221021522521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44264.

The product of its (nonzero) digits is 1600, while the sum is 26.

Adding to 1221021522521 its reverse (1252251201221), we get a palindrome (2473272723742).

The spelling of 1221021522521 in words is "one trillion, two hundred twenty-one billion, twenty-one million, five hundred twenty-two thousand, five hundred twenty-one".