68291021 has 6 divisors (see below), whose sum is σ = 68851050. Its totient is φ = 67732496.

The previous prime is 68290991. The next prime is 68291033. The reversal of 68291021 is 12019286.

It can be written as a sum of positive squares in 3 ways, for example, as 40780996 + 27510025 = 6386^2 + 5245^2 .

It is not a de Polignac number, because 68291021 - 2¹⁰ = 68289997 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 (68291051) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 100535 + ... + 101211.

It is an arithmetic number, because the mean of its divisors is an integer number (11475175).

Almost surely, 2^68291021 is an apocalyptic number.

It is an amenable number.

68291021 is a deficient number, since it is larger than the sum of its proper divisors (560029).

68291021 is an frugal number, since it uses more digits than its factorization.

68291021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503 (or 826 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 68291021 is about 8263.8381518517. The cubic root of 68291021 is about 408.7469596110.

The spelling of 68291021 in words is "sixty-eight million, two hundred ninety-one thousand, twenty-one".