31772221 has 4 divisors (see below), whose sum is σ = 34216252. Its totient is φ = 29328192.

The previous prime is 31772207. The next prime is 31772231. The reversal of 31772221 is 12227713.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12227713 = 3461 ⋅3533.

It can be written as a sum of positive squares in 2 ways, for example, as 18156121 + 13616100 = 4261^2 + 3690^2 .

It is a cyclic number.

It is not a de Polignac number, because 31772221 - 2⁵ = 31772189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31772231) 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, 1221996 + ... + 1222021.

It is an arithmetic number, because the mean of its divisors is an integer number (8554063).

Almost surely, 2^31772221 is an apocalyptic number.

It is an amenable number.

31772221 is a deficient number, since it is larger than the sum of its proper divisors (2444031).

31772221 is a wasteful number, since it uses less digits than its factorization.

31772221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2444030.

The product of its digits is 1176, while the sum is 25.

The square root of 31772221 is about 5636.6852848106. The cubic root of 31772221 is about 316.7251313413.

Adding to 31772221 its reverse (12227713), we get a palindrome (43999934).

The spelling of 31772221 in words is "thirty-one million, seven hundred seventy-two thousand, two hundred twenty-one".