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31861997 = 139229223
BaseRepresentation
bin111100110001…
…0110011101101
32012221202102222
41321202303231
531124040442
63054525125
7534552056
oct171426355
965852388
1031861997
1116a92432
12a8067a5
1367a766b
14433572d
152be58d2
hex1e62ced

31861997 has 4 divisors (see below), whose sum is σ = 32091360. Its totient is φ = 31632636.

The previous prime is 31861967. The next prime is 31862023. The reversal of 31861997 is 79916813.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 79916813 = 174700989.

It is a cyclic number.

It is not a de Polignac number, because 31861997 - 210 = 31860973 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 (31861937) 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, 114473 + ... + 114750.

It is an arithmetic number, because the mean of its divisors is an integer number (8022840).

Almost surely, 231861997 is an apocalyptic number.

It is an amenable number.

31861997 is a deficient number, since it is larger than the sum of its proper divisors (229363).

31861997 is a wasteful number, since it uses less digits than its factorization.

31861997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229362.

The product of its digits is 81648, while the sum is 44.

The square root of 31861997 is about 5644.6432128169. The cubic root of 31861997 is about 317.0231650219.

The spelling of 31861997 in words is "thirty-one million, eight hundred sixty-one thousand, nine hundred ninety-seven".

Divisors: 1 139 229223 31861997