161623531 has 2 divisors, whose sum is σ = 161623532. Its totient is φ = 161623530.

The previous prime is 161623529. The next prime is 161623537. The reversal of 161623531 is 135326161.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161623531 - 2¹ = 161623529 is a prime.

It is a super-2 number, since 2×161623531² = 52244331545815922, which contains 22 as substring.

Together with 161623529, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 161623531.

It is not a weakly prime, because it can be changed into another prime (161623537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80811765 + 80811766.

It is an arithmetic number, because the mean of its divisors is an integer number (80811766).

Almost surely, 2^161623531 is an apocalyptic number.

161623531 is a deficient number, since it is larger than the sum of its proper divisors (1).

161623531 is an equidigital number, since it uses as much as digits as its factorization.

161623531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 28.

The square root of 161623531 is about 12713.1243602822. The cubic root of 161623531 is about 544.7135728050.

Adding to 161623531 its reverse (135326161), we get a palindrome (296949692).

The spelling of 161623531 in words is "one hundred sixty-one million, six hundred twenty-three thousand, five hundred thirty-one".