78921505 has 32 divisors (see below), whose sum is σ = 107412480. Its totient is φ = 55261440.

The previous prime is 78921457. The next prime is 78921529. The reversal of 78921505 is 50512987.

It is not a de Polignac number, because 78921505 - 2¹³ = 78913313 is a prime.

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 31 ways as a sum of consecutive naturals, for example, 106426 + ... + 107164.

It is an arithmetic number, because the mean of its divisors is an integer number (3356640).

Almost surely, 2^78921505 is an apocalyptic number.

It is an amenable number.

78921505 is a deficient number, since it is larger than the sum of its proper divisors (28490975).

78921505 is a wasteful number, since it uses less digits than its factorization.

78921505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 841.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 78921505 is about 8883.7776311657. Note that the first 3 decimals coincide. The cubic root of 78921505 is about 428.9418818870.

The spelling of 78921505 in words is "seventy-eight million, nine hundred twenty-one thousand, five hundred five".