78123021 has 32 divisors (see below), whose sum is σ = 110899200. Its totient is φ = 48859200.

The previous prime is 78122987. The next prime is 78123037. The reversal of 78123021 is 12032187.

It is not a de Polignac number, because 78123021 - 2⁷ = 78122893 is a prime.

It is a super-2 number, since 2×78123021² = 12206412820332882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78122982 and 78123000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78123061) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 517296 + ... + 517446.

It is an arithmetic number, because the mean of its divisors is an integer number (3465600).

Almost surely, 2^78123021 is an apocalyptic number.

It is an amenable number.

78123021 is a deficient number, since it is larger than the sum of its proper divisors (32776179).

78123021 is a wasteful number, since it uses less digits than its factorization.

78123021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 78123021 is about 8838.7228149773. The cubic root of 78123021 is about 427.4903769935.

The spelling of 78123021 in words is "seventy-eight million, one hundred twenty-three thousand, twenty-one".