77880781 has 4 divisors (see below), whose sum is σ = 84960864. Its totient is φ = 70800700.

The previous prime is 77880769. The next prime is 77880799. The reversal of 77880781 is 18708877.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18708877 = 11 ⋅1700807.

It is a cyclic number.

It is not a de Polignac number, because 77880781 - 2⁷ = 77880653 is a prime.

It is a super-2 number, since 2×77880781² = 12130832098339922, 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 (77880701) 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, 3540025 + ... + 3540046.

It is an arithmetic number, because the mean of its divisors is an integer number (21240216).

Almost surely, 2^77880781 is an apocalyptic number.

It is an amenable number.

77880781 is a deficient number, since it is larger than the sum of its proper divisors (7080083).

77880781 is a wasteful number, since it uses less digits than its factorization.

77880781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7080082.

The product of its (nonzero) digits is 175616, while the sum is 46.

The square root of 77880781 is about 8825.0088385225. The cubic root of 77880781 is about 427.0480725128.

The spelling of 77880781 in words is "seventy-seven million, eight hundred eighty thousand, seven hundred eighty-one".