161221122001 has 4 divisors (see below), whose sum is σ = 163627407472. Its totient is φ = 158814836532.

The previous prime is 161221121983. The next prime is 161221122053. The reversal of 161221122001 is 100221122161.

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 a cyclic number.

It is not a de Polignac number, because 161221122001 - 2²³ = 161212733393 is a prime.

It is a super-2 number, since 2×161221122001² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161221122001.

It is not an unprimeable number, because it can be changed into a prime (161221122071) 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, 1203142635 + ... + 1203142768.

It is an arithmetic number, because the mean of its divisors is an integer number (40906851868).

Almost surely, 2^161221122001 is an apocalyptic number.

It is an amenable number.

161221122001 is a deficient number, since it is larger than the sum of its proper divisors (2406285471).

161221122001 is an equidigital number, since it uses as much as digits as its factorization.

161221122001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2406285470.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 161221122001 its reverse (100221122161), we get a palindrome (261442244162).

The spelling of 161221122001 in words is "one hundred sixty-one billion, two hundred twenty-one million, one hundred twenty-two thousand, one".