68521981 has 8 divisors (see below), whose sum is σ = 74839104. Its totient is φ = 62219520.

The previous prime is 68521967. The next prime is 68522009. The reversal of 68521981 is 18912586.

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

It is not a de Polignac number, because 68521981 - 2¹⁷ = 68390909 is a prime.

It is a super-2 number, since 2×68521981² = 9390523760328722, 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 (68521681) 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, 7645 + ... + 13981.

It is an arithmetic number, because the mean of its divisors is an integer number (9354888).

Almost surely, 2^68521981 is an apocalyptic number.

It is an amenable number.

68521981 is a deficient number, since it is larger than the sum of its proper divisors (6317123).

68521981 is a wasteful number, since it uses less digits than its factorization.

68521981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7331.

The product of its digits is 34560, while the sum is 40.

The square root of 68521981 is about 8277.8004928846. The cubic root of 68521981 is about 409.2072347250.

The spelling of 68521981 in words is "sixty-eight million, five hundred twenty-one thousand, nine hundred eighty-one".