161649989 has 4 divisors (see below), whose sum is σ = 162584556. Its totient is φ = 160715424.

The previous prime is 161649979. The next prime is 161649997. The reversal of 161649989 is 989946161.

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: 989946161 = 229 ⋅4322909.

It can be written as a sum of positive squares in 2 ways, for example, as 77616100 + 84033889 = 8810^2 + 9167^2 .

It is a cyclic number.

It is not a de Polignac number, because 161649989 - 2¹² = 161645893 is a prime.

It is a super-2 number, since 2×161649989² = 52261437887400242, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161649989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161649949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 467024 + ... + 467369.

It is an arithmetic number, because the mean of its divisors is an integer number (40646139).

Almost surely, 2^161649989 is an apocalyptic number.

It is an amenable number.

161649989 is a deficient number, since it is larger than the sum of its proper divisors (934567).

161649989 is an equidigital number, since it uses as much as digits as its factorization.

161649989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 934566.

The product of its digits is 839808, while the sum is 53.

The square root of 161649989 is about 12714.1648958947. The cubic root of 161649989 is about 544.7432946433.

The spelling of 161649989 in words is "one hundred sixty-one million, six hundred forty-nine thousand, nine hundred eighty-nine".