78402505 has 4 divisors (see below), whose sum is σ = 94083012. Its totient is φ = 62722000.

The previous prime is 78402473. The next prime is 78402539. The reversal of 78402505 is 50520487.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29626249 + 48776256 = 5443^2 + 6984^2 .

It is not a de Polignac number, because 78402505 - 2⁵ = 78402473 is a prime.

It is a super-2 number, since 2×78402505² = 12293905580550050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 7840246 + ... + 7840255.

It is an arithmetic number, because the mean of its divisors is an integer number (23520753).

Almost surely, 2^78402505 is an apocalyptic number.

It is an amenable number.

78402505 is a deficient number, since it is larger than the sum of its proper divisors (15680507).

78402505 is a wasteful number, since it uses less digits than its factorization.

78402505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15680506.

The product of its (nonzero) digits is 11200, while the sum is 31.

The square root of 78402505 is about 8854.5189027976. The cubic root of 78402505 is about 427.9995505425. Note that the first 3 decimals are identical.

The spelling of 78402505 in words is "seventy-eight million, four hundred two thousand, five hundred five".