1221543100451 has 16 divisors (see below), whose sum is σ = 1313345525760. Its totient is φ = 1132497463680.

The previous prime is 1221543100441. The next prime is 1221543100493. The reversal of 1221543100451 is 1540013451221.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1221543100451 - 2³⁰ = 1220469358627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221543100441) 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, 8084486 + ... + 8234196.

It is an arithmetic number, because the mean of its divisors is an integer number (82084095360).

Almost surely, 2^{1221543100451} is an apocalyptic number.

1221543100451 is a deficient number, since it is larger than the sum of its proper divisors (91802425309).

1221543100451 is a wasteful number, since it uses less digits than its factorization.

1221543100451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158914.

The product of its (nonzero) digits is 4800, while the sum is 29.

Adding to 1221543100451 its reverse (1540013451221), we get a palindrome (2761556551672).

The spelling of 1221543100451 in words is "one trillion, two hundred twenty-one billion, five hundred forty-three million, one hundred thousand, four hundred fifty-one".