179920021 has 2 divisors, whose sum is σ = 179920022. Its totient is φ = 179920020.

The previous prime is 179920009. The next prime is 179920043. The reversal of 179920021 is 120029971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 173211921 + 6708100 = 13161^2 + 2590^2 .

It is an emirp because it is prime and its reverse (120029971) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 179920021 - 2¹³ = 179911829 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (179920121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 89960010 + 89960011.

It is an arithmetic number, because the mean of its divisors is an integer number (89960011).

Almost surely, 2^179920021 is an apocalyptic number.

It is an amenable number.

179920021 is a deficient number, since it is larger than the sum of its proper divisors (1).

179920021 is an equidigital number, since it uses as much as digits as its factorization.

179920021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 179920021 is about 13413.4268924835. The cubic root of 179920021 is about 564.5379792503.

Adding to 179920021 its reverse (120029971), we get a palindrome (299949992).

The spelling of 179920021 in words is "one hundred seventy-nine million, nine hundred twenty thousand, twenty-one".