78751661 has 4 divisors (see below), whose sum is σ = 79020732. Its totient is φ = 78482592.

The previous prime is 78751613. The next prime is 78751669. The reversal of 78751661 is 16615787.

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 40386025 + 38365636 = 6355^2 + 6194^2 .

It is a cyclic number.

It is not a de Polignac number, because 78751661 - 2²⁶ = 11642797 is a prime.

It is a super-2 number, since 2×78751661² = 12403648220517842, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78751669) 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, 134096 + ... + 134681.

It is an arithmetic number, because the mean of its divisors is an integer number (19755183).

Almost surely, 2^78751661 is an apocalyptic number.

It is an amenable number.

78751661 is a deficient number, since it is larger than the sum of its proper divisors (269071).

78751661 is a wasteful number, since it uses less digits than its factorization.

78751661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269070.

The product of its digits is 70560, while the sum is 41.

The square root of 78751661 is about 8874.2132609038. The cubic root of 78751661 is about 428.6339576648.

The spelling of 78751661 in words is "seventy-eight million, seven hundred fifty-one thousand, six hundred sixty-one".