100561001221 has 4 divisors (see below), whose sum is σ = 106476354252. Its totient is φ = 94645648192.

The previous prime is 100561001207. The next prime is 100561001251. The reversal of 100561001221 is 122100165001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 55665324225 + 44895676996 = 235935^2 + 211886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100561001221 is a prime.

It is a super-2 number, since 2×100561001221² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100561001251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2957676490 + ... + 2957676523.

It is an arithmetic number, because the mean of its divisors is an integer number (26619088563).

Almost surely, 2^100561001221 is an apocalyptic number.

It is an amenable number.

100561001221 is a deficient number, since it is larger than the sum of its proper divisors (5915353031).

100561001221 is an equidigital number, since it uses as much as digits as its factorization.

100561001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5915353030.

The product of its (nonzero) digits is 120, while the sum is 19.

Adding to 100561001221 its reverse (122100165001), we get a palindrome (222661166222).

The spelling of 100561001221 in words is "one hundred billion, five hundred sixty-one million, one thousand, two hundred twenty-one".