161572821 has 16 divisors (see below), whose sum is σ = 222440448. Its totient is φ = 104241600.

The previous prime is 161572819. The next prime is 161572867. The reversal of 161572821 is 128275161.

It is not a de Polignac number, because 161572821 - 2¹ = 161572819 is a prime.

It is a super-2 number, since 2×161572821² = 52211552971796082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161572121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17391 + ... + 25011.

It is an arithmetic number, because the mean of its divisors is an integer number (13902528).

Almost surely, 2^161572821 is an apocalyptic number.

It is an amenable number.

161572821 is a deficient number, since it is larger than the sum of its proper divisors (60867627).

161572821 is a wasteful number, since it uses less digits than its factorization.

161572821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7852.

The product of its digits is 6720, while the sum is 33.

The square root of 161572821 is about 12711.1298081642. The cubic root of 161572821 is about 544.6565981914.

The spelling of 161572821 in words is "one hundred sixty-one million, five hundred seventy-two thousand, eight hundred twenty-one".