161512221531 has 8 divisors (see below), whose sum is σ = 215365173760. Its totient is φ = 107667041832.

The previous prime is 161512221473. The next prime is 161512221547. The reversal of 161512221531 is 135122215161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161512221531 - 2¹⁵ = 161512188763 is a prime.

It is a super-2 number, since 2×161512221531² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161512221581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1894471 + ... + 1977888.

It is an arithmetic number, because the mean of its divisors is an integer number (26920646720).

Almost surely, 2^161512221531 is an apocalyptic number.

161512221531 is a deficient number, since it is larger than the sum of its proper divisors (53852952229).

161512221531 is a wasteful number, since it uses less digits than its factorization.

161512221531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3886265.

The product of its digits is 3600, while the sum is 30.

Adding to 161512221531 its reverse (135122215161), we get a palindrome (296634436692).

The spelling of 161512221531 in words is "one hundred sixty-one billion, five hundred twelve million, two hundred twenty-one thousand, five hundred thirty-one".