1221021501253 has 16 divisors (see below), whose sum is σ = 1261640540160. Its totient is φ = 1180480100400.

The previous prime is 1221021501229. The next prime is 1221021501379. The reversal of 1221021501253 is 3521051201221.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221021501253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221021501053) 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, 193471968 + ... + 193478278.

It is an arithmetic number, because the mean of its divisors is an integer number (78852533760).

Almost surely, 2^{1221021501253} is an apocalyptic number.

It is an amenable number.

1221021501253 is a deficient number, since it is larger than the sum of its proper divisors (40619038907).

1221021501253 is a wasteful number, since it uses less digits than its factorization.

1221021501253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11448.

The product of its (nonzero) digits is 1200, while the sum is 25.

Adding to 1221021501253 its reverse (3521051201221), we get a palindrome (4742072702474).

The spelling of 1221021501253 in words is "one trillion, two hundred twenty-one billion, twenty-one million, five hundred one thousand, two hundred fifty-three".