78212405 has 8 divisors (see below), whose sum is σ = 94716600. Its totient is φ = 61995456.

The previous prime is 78212401. The next prime is 78212429. The reversal of 78212405 is 50421287.

It can be written as a sum of positive squares in 4 ways, for example, as 36312676 + 41899729 = 6026^2 + 6473^2 .

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 78212405 - 2² = 78212401 is a prime.

It is a super-2 number, since 2×78212405² = 12234360591768050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78212401) 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, 71210 + ... + 72299.

It is an arithmetic number, because the mean of its divisors is an integer number (11839575).

Almost surely, 2^78212405 is an apocalyptic number.

It is an amenable number.

78212405 is a deficient number, since it is larger than the sum of its proper divisors (16504195).

78212405 is a wasteful number, since it uses less digits than its factorization.

78212405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143623.

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 78212405 is about 8843.7777561402. Note that the first 4 decimals coincide. The cubic root of 78212405 is about 427.6533517297.

The spelling of 78212405 in words is "seventy-eight million, two hundred twelve thousand, four hundred five".