161065705571021 has 4 divisors (see below), whose sum is σ = 164811419654112. Its totient is φ = 157319991487932.

The previous prime is 161065705571009. The next prime is 161065705571027. The reversal of 161065705571021 is 120175507560161.

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 161065705571021 - 2¹⁸ = 161065705308877 is a prime.

It is a super-2 number, since 2×161065705571021² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161065705571027) 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, 1872857041481 + ... + 1872857041566.

It is an arithmetic number, because the mean of its divisors is an integer number (41202854913528).

Almost surely, 2^{161065705571021} is an apocalyptic number.

It is an amenable number.

161065705571021 is a deficient number, since it is larger than the sum of its proper divisors (3745714083091).

161065705571021 is an equidigital number, since it uses as much as digits as its factorization.

161065705571021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3745714083090.

The product of its (nonzero) digits is 441000, while the sum is 47.

The spelling of 161065705571021 in words is "one hundred sixty-one trillion, sixty-five billion, seven hundred five million, five hundred seventy-one thousand, twenty-one".