55777781 has 4 divisors (see below), whose sum is σ = 56179200. Its totient is φ = 55376364.

The previous prime is 55777741. The next prime is 55777789. The reversal of 55777781 is 18777755.

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 a de Polignac number, because none of the positive numbers 2^k-55777781 is a prime.

It is a super-2 number, since 2×55777781² = 6222321706567922, 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 (55777789) 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, 200501 + ... + 200778.

It is an arithmetic number, because the mean of its divisors is an integer number (14044800).

Almost surely, 2^55777781 is an apocalyptic number.

It is an amenable number.

55777781 is a deficient number, since it is larger than the sum of its proper divisors (401419).

55777781 is a wasteful number, since it uses less digits than its factorization.

55777781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401418.

The product of its digits is 480200, while the sum is 47.

The square root of 55777781 is about 7468.4523831916. The cubic root of 55777781 is about 382.0795065817.

The spelling of 55777781 in words is "fifty-five million, seven hundred seventy-seven thousand, seven hundred eighty-one".