55151721557 has 2 divisors, whose sum is σ = 55151721558. Its totient is φ = 55151721556.

The previous prime is 55151721533. The next prime is 55151721577. The reversal of 55151721557 is 75512715155.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49197901636 + 5953819921 = 221806^2 + 77161^2 .

It is a cyclic number.

It is not a de Polignac number, because 55151721557 - 2¹⁸ = 55151459413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55151721577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27575860778 + 27575860779.

It is an arithmetic number, because the mean of its divisors is an integer number (27575860779).

Almost surely, 2^55151721557 is an apocalyptic number.

It is an amenable number.

55151721557 is a deficient number, since it is larger than the sum of its proper divisors (1).

55151721557 is an equidigital number, since it uses as much as digits as its factorization.

55151721557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 306250, while the sum is 44.

The spelling of 55151721557 in words is "fifty-five billion, one hundred fifty-one million, seven hundred twenty-one thousand, five hundred fifty-seven".