78307021 has 8 divisors (see below), whose sum is σ = 84438144. Its totient is φ = 72191280.

The previous prime is 78307013. The next prime is 78307039. The reversal of 78307021 is 12070387.

It is a happy number.

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 78307021 - 2³ = 78307013 is a prime.

It is a super-2 number, since 2×78307021² = 12263979075788882, 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 (78307081) 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, 8136 + ... + 14926.

It is an arithmetic number, because the mean of its divisors is an integer number (10554768).

Almost surely, 2^78307021 is an apocalyptic number.

It is an amenable number.

78307021 is a deficient number, since it is larger than the sum of its proper divisors (6131123).

78307021 is a wasteful number, since it uses less digits than its factorization.

78307021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7691.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 78307021 is about 8849.1254370135. The cubic root of 78307021 is about 427.8257307962.

The spelling of 78307021 in words is "seventy-eight million, three hundred seven thousand, twenty-one".