78355561 has 4 divisors (see below), whose sum is σ = 78874624. Its totient is φ = 77836500.

The previous prime is 78355559. The next prime is 78355573. The reversal of 78355561 is 16555387.

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 78355561 - 2¹ = 78355559 is a prime.

It is a super-2 number, since 2×78355561² = 12279187879249442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78350561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259305 + ... + 259606.

It is an arithmetic number, because the mean of its divisors is an integer number (19718656).

Almost surely, 2^78355561 is an apocalyptic number.

It is an amenable number.

78355561 is a deficient number, since it is larger than the sum of its proper divisors (519063).

78355561 is a wasteful number, since it uses less digits than its factorization.

78355561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 519062.

The product of its digits is 126000, while the sum is 40.

The square root of 78355561 is about 8851.8676560373. The cubic root of 78355561 is about 427.9141110007.

The spelling of 78355561 in words is "seventy-eight million, three hundred fifty-five thousand, five hundred sixty-one".