68628781 has 8 divisors (see below), whose sum is σ = 74233880. Its totient is φ = 63070272.

The previous prime is 68628773. The next prime is 68628787. The reversal of 68628781 is 18782686.

It can be written as a sum of positive squares in 4 ways, for example, as 21706281 + 46922500 = 4659^2 + 6850^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 68628781 - 2³ = 68628773 is a prime.

It is a super-2 number, since 2×68628781² = 9419819163091922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68628787) 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, 8550 + ... + 14503.

It is an arithmetic number, because the mean of its divisors is an integer number (9279235).

Almost surely, 2^68628781 is an apocalyptic number.

It is an amenable number.

68628781 is a deficient number, since it is larger than the sum of its proper divisors (5605099).

68628781 is a wasteful number, since it uses less digits than its factorization.

68628781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23295.

The product of its digits is 258048, while the sum is 46.

The square root of 68628781 is about 8284.2489701843. The cubic root of 68628781 is about 409.4197244301.

It can be divided in two parts, 68 and 628781, that added together give a square (628849 = 793²).

The spelling of 68628781 in words is "sixty-eight million, six hundred twenty-eight thousand, seven hundred eighty-one".