78131261 has 4 divisors (see below), whose sum is σ = 84141372. Its totient is φ = 72121152.

The previous prime is 78131257. The next prime is 78131267. The reversal of 78131261 is 16213187.

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

It can be written as a sum of positive squares in 2 ways, for example, as 25060036 + 53071225 = 5006^2 + 7285^2 .

It is a cyclic number.

It is not a de Polignac number, because 78131261 - 2² = 78131257 is a prime.

It is a super-2 number, since 2×78131261² = 12208987890900242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78131267) 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, 3005036 + ... + 3005061.

It is an arithmetic number, because the mean of its divisors is an integer number (21035343).

Almost surely, 2^78131261 is an apocalyptic number.

It is an amenable number.

78131261 is a deficient number, since it is larger than the sum of its proper divisors (6010111).

78131261 is a wasteful number, since it uses less digits than its factorization.

78131261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6010110.

The product of its digits is 2016, while the sum is 29.

The square root of 78131261 is about 8839.1889333807. The cubic root of 78131261 is about 427.5054062675.

The spelling of 78131261 in words is "seventy-eight million, one hundred thirty-one thousand, two hundred sixty-one".