68634721 has 4 divisors (see below), whose sum is σ = 68700352. Its totient is φ = 68569092.

The previous prime is 68634719. The next prime is 68634739. The reversal of 68634721 is 12743686.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12743686 = 2 ⋅6371843.

It is a cyclic number.

It is not a de Polignac number, because 68634721 - 2¹ = 68634719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68634781) 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, 31221 + ... + 33346.

It is an arithmetic number, because the mean of its divisors is an integer number (17175088).

Almost surely, 2^68634721 is an apocalyptic number.

It is an amenable number.

68634721 is a deficient number, since it is larger than the sum of its proper divisors (65631).

68634721 is a wasteful number, since it uses less digits than its factorization.

68634721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65630.

The product of its digits is 48384, while the sum is 37.

The square root of 68634721 is about 8284.6074741052. The cubic root of 68634721 is about 409.4315362044.

The spelling of 68634721 in words is "sixty-eight million, six hundred thirty-four thousand, seven hundred twenty-one".