161356543501 has 4 divisors (see below), whose sum is σ = 161362297404. Its totient is φ = 161350789600.

The previous prime is 161356543441. The next prime is 161356543507. The reversal of 161356543501 is 105345653161.

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 147064580100 + 14291963401 = 383490^2 + 119549^2 .

It is a cyclic number.

It is not a de Polignac number, because 161356543501 - 2²¹ = 161354446349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161356543507) 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, 2834680 + ... + 2891041.

It is an arithmetic number, because the mean of its divisors is an integer number (40340574351).

Almost surely, 2^161356543501 is an apocalyptic number.

It is an amenable number.

161356543501 is a deficient number, since it is larger than the sum of its proper divisors (5753903).

161356543501 is an equidigital number, since it uses as much as digits as its factorization.

161356543501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5753902.

The product of its (nonzero) digits is 162000, while the sum is 40.

The spelling of 161356543501 in words is "one hundred sixty-one billion, three hundred fifty-six million, five hundred forty-three thousand, five hundred one".