68487781 has 4 divisors (see below), whose sum is σ = 72516492. Its totient is φ = 64459072.

The previous prime is 68487743. The next prime is 68487803. The reversal of 68487781 is 18778486.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 59814756 + 8673025 = 7734^2 + 2945^2 .

It is a cyclic number.

It is not a de Polignac number, because 68487781 - 2⁹ = 68487269 is a prime.

It is a super-2 number, since 2×68487781² = 9381152292607922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68487281) 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, 2014330 + ... + 2014363.

It is an arithmetic number, because the mean of its divisors is an integer number (18129123).

Almost surely, 2^68487781 is an apocalyptic number.

It is an amenable number.

68487781 is a deficient number, since it is larger than the sum of its proper divisors (4028711).

68487781 is a wasteful number, since it uses less digits than its factorization.

68487781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4028710.

The product of its digits is 602112, while the sum is 49.

The square root of 68487781 is about 8275.7344689157. The cubic root of 68487781 is about 409.1391435996.

The spelling of 68487781 in words is "sixty-eight million, four hundred eighty-seven thousand, seven hundred eighty-one".