31781979 has 6 divisors (see below), whose sum is σ = 45907316. Its totient is φ = 21187980.

The previous prime is 31781977. The next prime is 31781983. The reversal of 31781979 is 97918713.

It is not a de Polignac number, because 31781979 - 2¹ = 31781977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31781977) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1765657 + ... + 1765674.

Almost surely, 2^31781979 is an apocalyptic number.

31781979 is a deficient number, since it is larger than the sum of its proper divisors (14125337).

31781979 is a wasteful number, since it uses less digits than its factorization.

31781979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3531337 (or 3531334 counting only the distinct ones).

The product of its digits is 95256, while the sum is 45.

The square root of 31781979 is about 5637.5507979973. The cubic root of 31781979 is about 316.7575526136.

The spelling of 31781979 in words is "thirty-one million, seven hundred eighty-one thousand, nine hundred seventy-nine".