55780731721 has 16 divisors (see below), whose sum is σ = 69387470208. Its totient is φ = 44055532800.

The previous prime is 55780731719. The next prime is 55780731757. The reversal of 55780731721 is 12713708755.

It is a cyclic number.

It is not a de Polignac number, because 55780731721 - 2¹ = 55780731719 is a prime.

It is a super-2 number, since 2×55780731721² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55780731701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11470365 + ... + 11475226.

It is an arithmetic number, because the mean of its divisors is an integer number (4336716888).

Almost surely, 2^55780731721 is an apocalyptic number.

It is an amenable number.

55780731721 is a deficient number, since it is larger than the sum of its proper divisors (13606738487).

55780731721 is a wasteful number, since it uses less digits than its factorization.

55780731721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22945632.

The product of its (nonzero) digits is 411600, while the sum is 46.

The spelling of 55780731721 in words is "fifty-five billion, seven hundred eighty million, seven hundred thirty-one thousand, seven hundred twenty-one".