78242921 has 8 divisors (see below), whose sum is σ = 80058240. Its totient is φ = 76433968.

The previous prime is 78242917. The next prime is 78242947. The reversal of 78242921 is 12924287.

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

It is a cyclic number.

It is not a de Polignac number, because 78242921 - 2² = 78242917 is a prime.

It is a super-2 number, since 2×78242921² = 12243909373224482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78242981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30590 + ... + 33048.

It is an arithmetic number, because the mean of its divisors is an integer number (10007280).

Almost surely, 2^78242921 is an apocalyptic number.

It is an amenable number.

78242921 is a deficient number, since it is larger than the sum of its proper divisors (1815319).

78242921 is a wasteful number, since it uses less digits than its factorization.

78242921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3183.

The product of its digits is 16128, while the sum is 35.

The square root of 78242921 is about 8845.5028686898. The cubic root of 78242921 is about 427.7089634228.

The spelling of 78242921 in words is "seventy-eight million, two hundred forty-two thousand, nine hundred twenty-one".