161631031251 has 4 divisors (see below), whose sum is σ = 215508041672. Its totient is φ = 107754020832.

The previous prime is 161631031249. The next prime is 161631031283. The reversal of 161631031251 is 152130136161.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 161631031251 - 2¹ = 161631031249 is a prime.

It is a super-3 number, since 3×161631031251³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161631031951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26938505206 + ... + 26938505211.

It is an arithmetic number, because the mean of its divisors is an integer number (53877010418).

Almost surely, 2^161631031251 is an apocalyptic number.

161631031251 is a deficient number, since it is larger than the sum of its proper divisors (53877010421).

161631031251 is an equidigital number, since it uses as much as digits as its factorization.

161631031251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53877010420.

The product of its (nonzero) digits is 3240, while the sum is 30.

The spelling of 161631031251 in words is "one hundred sixty-one billion, six hundred thirty-one million, thirty-one thousand, two hundred fifty-one".