1221400526561 has 8 divisors (see below), whose sum is σ = 1240306617600. Its totient is φ = 1202580568800.

The previous prime is 1221400526557. The next prime is 1221400526569. The reversal of 1221400526561 is 1656250041221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221400526561 - 2² = 1221400526557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221400526569) 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, 21504740 + ... + 21561461.

It is an arithmetic number, because the mean of its divisors is an integer number (155038327200).

Almost surely, 2^{1221400526561} is an apocalyptic number.

It is an amenable number.

1221400526561 is a deficient number, since it is larger than the sum of its proper divisors (18906091039).

1221400526561 is an equidigital number, since it uses as much as digits as its factorization.

1221400526561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43066639.

The product of its (nonzero) digits is 28800, while the sum is 35.

Adding to 1221400526561 its reverse (1656250041221), we get a palindrome (2877650567782).

The spelling of 1221400526561 in words is "one trillion, two hundred twenty-one billion, four hundred million, five hundred twenty-six thousand, five hundred sixty-one".