56551767781 has 2 divisors, whose sum is σ = 56551767782. Its totient is φ = 56551767780.

The previous prime is 56551767757. The next prime is 56551767787. The reversal of 56551767781 is 18776715565.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55056398881 + 1495368900 = 234641^2 + 38670^2 .

It is a cyclic number.

It is not a de Polignac number, because 56551767781 - 2⁵ = 56551767749 is a prime.

It is a super-2 number, since 2×56551767781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56551767787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28275883890 + 28275883891.

It is an arithmetic number, because the mean of its divisors is an integer number (28275883891).

Almost surely, 2^56551767781 is an apocalyptic number.

It is an amenable number.

56551767781 is a deficient number, since it is larger than the sum of its proper divisors (1).

56551767781 is an equidigital number, since it uses as much as digits as its factorization.

56551767781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12348000, while the sum is 58.

The spelling of 56551767781 in words is "fifty-six billion, five hundred fifty-one million, seven hundred sixty-seven thousand, seven hundred eighty-one".