78135661 has 4 divisors (see below), whose sum is σ = 79124800. Its totient is φ = 77146524.

The previous prime is 78135643. The next prime is 78135671. The reversal of 78135661 is 16653187.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78135661 - 2¹¹ = 78133613 is a prime.

It is a super-2 number, since 2×78135661² = 12210363039813842, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78135661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78135611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 494451 + ... + 494608.

It is an arithmetic number, because the mean of its divisors is an integer number (19781200).

Almost surely, 2^78135661 is an apocalyptic number.

It is an amenable number.

78135661 is a deficient number, since it is larger than the sum of its proper divisors (989139).

78135661 is an equidigital number, since it uses as much as digits as its factorization.

78135661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 989138.

The product of its digits is 30240, while the sum is 37.

The square root of 78135661 is about 8839.4378214907. The cubic root of 78135661 is about 427.5134311752.

The spelling of 78135661 in words is "seventy-eight million, one hundred thirty-five thousand, six hundred sixty-one".