161021929 has 4 divisors (see below), whose sum is σ = 161137620. Its totient is φ = 160906240.

The previous prime is 161021881. The next prime is 161021933. The reversal of 161021929 is 929120161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 929120161 = 977 ⋅950993.

It can be written as a sum of positive squares in 2 ways, for example, as 38875225 + 122146704 = 6235^2 + 11052^2 .

It is a cyclic number.

It is not a de Polignac number, because 161021929 - 2¹³ = 161013737 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 161021929.

It is not an unprimeable number, because it can be changed into a prime (161028929) 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, 55732 + ... + 58549.

It is an arithmetic number, because the mean of its divisors is an integer number (40284405).

Almost surely, 2^161021929 is an apocalyptic number.

It is an amenable number.

161021929 is a deficient number, since it is larger than the sum of its proper divisors (115691).

161021929 is a wasteful number, since it uses less digits than its factorization.

161021929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115690.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 161021929 is about 12689.4416346820. The cubic root of 161021929 is about 544.0368804743.

The spelling of 161021929 in words is "one hundred sixty-one million, twenty-one thousand, nine hundred twenty-nine".