1261224221621 has 56 divisors (see below), whose sum is σ = 1623342931224. Its totient is φ = 973504465920.

The previous prime is 1261224221549. The next prime is 1261224221623.

1261224221621 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 4 ways, for example, as 150226008100 + 1110998213521 = 387590^2 + 1054039^2 .

It is not a de Polignac number, because 1261224221621 - 2³⁴ = 1244044352437 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261224221623) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 62696861 + ... + 62716973.

It is an arithmetic number, because the mean of its divisors is an integer number (28988266629).

Almost surely, 2^{1261224221621} is an apocalyptic number.

It is an amenable number.

1261224221621 is a deficient number, since it is larger than the sum of its proper divisors (362118709603).

1261224221621 is an frugal number, since it uses more digits than its factorization.

1261224221621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20209 (or 20174 counting only the distinct ones).

The product of its digits is 9216, while the sum is 32.

The spelling of 1261224221621 in words is "one trillion, two hundred sixty-one billion, two hundred twenty-four million, two hundred twenty-one thousand, six hundred twenty-one".