78143721 has 4 divisors (see below), whose sum is σ = 104191632. Its totient is φ = 52095812.

The previous prime is 78143717. The next prime is 78143729. The reversal of 78143721 is 12734187.

It is a happy number.

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: 12734187 = 3 ⋅4244729.

It is a cyclic number.

It is not a de Polignac number, because 78143721 - 2² = 78143717 is a prime.

It is a super-2 number, since 2×78143721² = 12212882263451682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78143729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13023951 + ... + 13023956.

It is an arithmetic number, because the mean of its divisors is an integer number (26047908).

Almost surely, 2^78143721 is an apocalyptic number.

It is an amenable number.

78143721 is a deficient number, since it is larger than the sum of its proper divisors (26047911).

78143721 is a wasteful number, since it uses less digits than its factorization.

78143721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26047910.

The product of its digits is 9408, while the sum is 33.

The square root of 78143721 is about 8839.8937210806. The cubic root of 78143721 is about 427.5281305657.

The spelling of 78143721 in words is "seventy-eight million, one hundred forty-three thousand, seven hundred twenty-one".