78211655 has 4 divisors (see below), whose sum is σ = 93853992. Its totient is φ = 62569320.

The previous prime is 78211649. The next prime is 78211669. The reversal of 78211655 is 55611287.

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

It is not a de Polignac number, because 78211655 - 2¹⁶ = 78146119 is a prime.

It is a super-2 number, since 2×78211655² = 12234125955678050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent 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, 7821161 + ... + 7821170.

It is an arithmetic number, because the mean of its divisors is an integer number (23463498).

Almost surely, 2^78211655 is an apocalyptic number.

78211655 is a deficient number, since it is larger than the sum of its proper divisors (15642337).

78211655 is a wasteful number, since it uses less digits than its factorization.

78211655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15642336.

The product of its digits is 16800, while the sum is 35.

The square root of 78211655 is about 8843.7353533448. The cubic root of 78211655 is about 427.6519847639.

The spelling of 78211655 in words is "seventy-eight million, two hundred eleven thousand, six hundred fifty-five".