67431781 has 8 divisors (see below), whose sum is σ = 68375384. Its totient is φ = 66493440.

The previous prime is 67431739. The next prime is 67431787. The reversal of 67431781 is 18713476.

It can be written as a sum of positive squares in 4 ways, for example, as 748225 + 66683556 = 865^2 + 8166^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-67431781 is a prime.

It is a super-2 number, since 2×67431781² = 9094090177663922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 67431781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67431787) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29251 + ... + 31471.

It is an arithmetic number, because the mean of its divisors is an integer number (8546923).

Almost surely, 2^67431781 is an apocalyptic number.

It is an amenable number.

67431781 is a deficient number, since it is larger than the sum of its proper divisors (943603).

67431781 is a wasteful number, since it uses less digits than its factorization.

67431781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2631.

The product of its digits is 28224, while the sum is 37.

The square root of 67431781 is about 8211.6856369445. The cubic root of 67431781 is about 407.0254296945.

The spelling of 67431781 in words is "sixty-seven million, four hundred thirty-one thousand, seven hundred eighty-one".