161661651 has 8 divisors (see below), whose sum is σ = 219082704. Its totient is φ = 106007520.

The previous prime is 161661637. The next prime is 161661677. The reversal of 161661651 is 156166161.

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

It is not a de Polignac number, because 161661651 - 2¹⁸ = 161399507 is a prime.

It is a super-2 number, since 2×161661651² = 52268978808091602, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161662651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 441516 + ... + 441881.

It is an arithmetic number, because the mean of its divisors is an integer number (27385338).

Almost surely, 2^161661651 is an apocalyptic number.

161661651 is a deficient number, since it is larger than the sum of its proper divisors (57421053).

161661651 is an equidigital number, since it uses as much as digits as its factorization.

161661651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 883461.

The product of its digits is 6480, while the sum is 33.

The square root of 161661651 is about 12714.6235099589. The cubic root of 161661651 is about 544.7563942288.

The spelling of 161661651 in words is "one hundred sixty-one million, six hundred sixty-one thousand, six hundred fifty-one".