78293021 has 4 divisors (see below), whose sum is σ = 78311772. Its totient is φ = 78274272.

The previous prime is 78293009. The next prime is 78293057. The reversal of 78293021 is 12039287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12039287 = 13 ⋅926099.

It can be written as a sum of positive squares in 2 ways, for example, as 68244121 + 10048900 = 8261^2 + 3170^2 .

It is a cyclic number.

It is not a de Polignac number, because 78293021 - 2⁶ = 78292957 is a prime.

It is a super-2 number, since 2×78293021² = 12259594274612882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78293521) 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, 41 + ... + 12513.

It is an arithmetic number, because the mean of its divisors is an integer number (19577943).

Almost surely, 2^78293021 is an apocalyptic number.

It is an amenable number.

78293021 is a deficient number, since it is larger than the sum of its proper divisors (18751).

78293021 is a wasteful number, since it uses less digits than its factorization.

78293021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18750.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 78293021 is about 8848.3343630313. The cubic root of 78293021 is about 427.8002332221.

The spelling of 78293021 in words is "seventy-eight million, two hundred ninety-three thousand, twenty-one".