78211121 has 4 divisors (see below), whose sum is σ = 78231792. Its totient is φ = 78190452.

The previous prime is 78211117. The next prime is 78211123. The reversal of 78211121 is 12111287.

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.

It is a cyclic number.

It is not a de Polignac number, because 78211121 - 2² = 78211117 is a prime.

It is a super-2 number, since 2×78211121² = 12233958896153282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78211123) 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, 2855 + ... + 12828.

It is an arithmetic number, because the mean of its divisors is an integer number (19557948).

Almost surely, 2^78211121 is an apocalyptic number.

It is an amenable number.

78211121 is a deficient number, since it is larger than the sum of its proper divisors (20671).

78211121 is a wasteful number, since it uses less digits than its factorization.

78211121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20670.

The product of its digits is 224, while the sum is 23.

The square root of 78211121 is about 8843.7051624305. The cubic root of 78211121 is about 427.6510114790.

It can be divided in two parts, 7 and 8211121, that added together give a palindrome (8211128).

The spelling of 78211121 in words is "seventy-eight million, two hundred eleven thousand, one hundred twenty-one".