161222731 has 4 divisors (see below), whose sum is σ = 161253000. Its totient is φ = 161192464.

The previous prime is 161222693. The next prime is 161222741. The reversal of 161222731 is 137222161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 137222161 = 19 ⋅7222219.

It is a cyclic number.

It is not a de Polignac number, because 161222731 - 2¹⁷ = 161091659 is a prime.

It is a super-2 number, since 2×161222731² = 51985537982196722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161222696 and 161222705.

It is not an unprimeable number, because it can be changed into a prime (161222741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4786 + ... + 18583.

It is an arithmetic number, because the mean of its divisors is an integer number (40313250).

Almost surely, 2^161222731 is an apocalyptic number.

161222731 is a deficient number, since it is larger than the sum of its proper divisors (30269).

161222731 is an equidigital number, since it uses as much as digits as its factorization.

161222731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30268.

The product of its digits is 1008, while the sum is 25.

The square root of 161222731 is about 12697.3513379760. The cubic root of 161222731 is about 544.2629331515.

Adding to 161222731 its reverse (137222161), we get a palindrome (298444892).

The spelling of 161222731 in words is "one hundred sixty-one million, two hundred twenty-two thousand, seven hundred thirty-one".