1221564528078 has 16 divisors (see below), whose sum is σ = 2447515290960. Its totient is φ = 406457136896.

The previous prime is 1221564528077. The next prime is 1221564528091. The reversal of 1221564528078 is 8708254651221.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221564528078.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221564528073) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 182756163 + ... + 182762846.

It is an arithmetic number, because the mean of its divisors is an integer number (152969705685).

Almost surely, 2^{1221564528078} is an apocalyptic number.

1221564528078 is an abundant number, since it is smaller than the sum of its proper divisors (1225950762882).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221564528078 is a wasteful number, since it uses less digits than its factorization.

1221564528078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365519571.

The product of its (nonzero) digits is 2150400, while the sum is 51.

The spelling of 1221564528078 in words is "one trillion, two hundred twenty-one billion, five hundred sixty-four million, five hundred twenty-eight thousand, seventy-eight".