55403121721 has 2 divisors, whose sum is σ = 55403121722. Its totient is φ = 55403121720.

The previous prime is 55403121701. The next prime is 55403121749. The reversal of 55403121721 is 12712130455.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 47260586025 + 8142535696 = 217395^2 + 90236^2 .

It is a cyclic number.

It is not a de Polignac number, because 55403121721 - 2²⁷ = 55268903993 is a prime.

It is not a weakly prime, because it can be changed into another prime (55403121701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27701560860 + 27701560861.

It is an arithmetic number, because the mean of its divisors is an integer number (27701560861).

Almost surely, 2^55403121721 is an apocalyptic number.

It is an amenable number.

55403121721 is a deficient number, since it is larger than the sum of its proper divisors (1).

55403121721 is an equidigital number, since it uses as much as digits as its factorization.

55403121721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8400, while the sum is 31.

The spelling of 55403121721 in words is "fifty-five billion, four hundred three million, one hundred twenty-one thousand, seven hundred twenty-one".