1221878427501 has 4 divisors (see below), whose sum is σ = 1629171236672. Its totient is φ = 814585618332.

The previous prime is 1221878427481. The next prime is 1221878427527. The reversal of 1221878427501 is 1057248781221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1221878427501 - 2¹⁰ = 1221878426477 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221878427541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203646404581 + ... + 203646404586.

It is an arithmetic number, because the mean of its divisors is an integer number (407292809168).

Almost surely, 2^{1221878427501} is an apocalyptic number.

It is an amenable number.

1221878427501 is a deficient number, since it is larger than the sum of its proper divisors (407292809171).

1221878427501 is an equidigital number, since it uses as much as digits as its factorization.

1221878427501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407292809170.

The product of its (nonzero) digits is 501760, while the sum is 48.

The spelling of 1221878427501 in words is "one trillion, two hundred twenty-one billion, eight hundred seventy-eight million, four hundred twenty-seven thousand, five hundred one".