31781228 has 12 divisors (see below), whose sum is σ = 58888872. Its totient is φ = 14955840.

The previous prime is 31781227. The next prime is 31781297. The reversal of 31781228 is 82218713.

It is a junction number, because it is equal to n+sod(n) for n = 31781194 and 31781203.

It is not an unprimeable number, because it can be changed into a prime (31781221) 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, 233618 + ... + 233753.

It is an arithmetic number, because the mean of its divisors is an integer number (4907406).

Almost surely, 2^31781228 is an apocalyptic number.

It is an amenable number.

31781228 is a deficient number, since it is larger than the sum of its proper divisors (27107644).

31781228 is a wasteful number, since it uses less digits than its factorization.

31781228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467392 (or 467390 counting only the distinct ones).

The product of its digits is 5376, while the sum is 32.

The square root of 31781228 is about 5637.4841906652. The cubic root of 31781228 is about 316.7550576274.

The spelling of 31781228 in words is "thirty-one million, seven hundred eighty-one thousand, two hundred twenty-eight".