78809531 has 4 divisors (see below), whose sum is σ = 79807200. Its totient is φ = 77811864.

The previous prime is 78809483. The next prime is 78809573. The reversal of 78809531 is 13590887.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 78809531 - 2¹⁰ = 78808507 is a prime.

It is a super-2 number, since 2×78809531² = 12421884352879922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78809581) 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, 498716 + ... + 498873.

It is an arithmetic number, because the mean of its divisors is an integer number (19951800).

Almost surely, 2^78809531 is an apocalyptic number.

78809531 is a deficient number, since it is larger than the sum of its proper divisors (997669).

78809531 is an equidigital number, since it uses as much as digits as its factorization.

78809531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 997668.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 78809531 is about 8877.4732328518. The cubic root of 78809531 is about 428.7389246516.

The spelling of 78809531 in words is "seventy-eight million, eight hundred nine thousand, five hundred thirty-one".