31221745 has 4 divisors (see below), whose sum is σ = 37466100. Its totient is φ = 24977392.

The previous prime is 31221739. The next prime is 31221761. The reversal of 31221745 is 54712213.

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: 54712213 = 3067 ⋅17839.

It can be written as a sum of positive squares in 2 ways, for example, as 15085456 + 16136289 = 3884^2 + 4017^2 .

It is a cyclic number.

It is not a de Polignac number, because 31221745 - 2¹⁵ = 31188977 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3122170 + ... + 3122179.

It is an arithmetic number, because the mean of its divisors is an integer number (9366525).

Almost surely, 2^31221745 is an apocalyptic number.

It is an amenable number.

31221745 is a deficient number, since it is larger than the sum of its proper divisors (6244355).

31221745 is an equidigital number, since it uses as much as digits as its factorization.

31221745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6244354.

The product of its digits is 1680, while the sum is 25.

The square root of 31221745 is about 5587.6421682137. The cubic root of 31221745 is about 314.8853029971.

Adding to 31221745 its reverse (54712213), we get a palindrome (85933958).

The spelling of 31221745 in words is "thirty-one million, two hundred twenty-one thousand, seven hundred forty-five".