31781997 has 16 divisors (see below), whose sum is σ = 50706880. Its totient is φ = 19557936.

The previous prime is 31781983. The next prime is 31782007. The reversal of 31781997 is 79918713.

It is not a de Polignac number, because 31781997 - 2⁸ = 31781741 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 (31781947) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44923 + ... + 45624.

It is an arithmetic number, because the mean of its divisors is an integer number (3169180).

Almost surely, 2^31781997 is an apocalyptic number.

It is an amenable number.

31781997 is a deficient number, since it is larger than the sum of its proper divisors (18924883).

31781997 is a wasteful number, since it uses less digits than its factorization.

31781997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90569 (or 90563 counting only the distinct ones).

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

The square root of 31781997 is about 5637.5523944350. The cubic root of 31781997 is about 316.7576124131.

The spelling of 31781997 in words is "thirty-one million, seven hundred eighty-one thousand, nine hundred ninety-seven".