1721136215545 has 4 divisors (see below), whose sum is σ = 2065363458660. Its totient is φ = 1376908972432.

The previous prime is 1721136215527. The next prime is 1721136215551. The reversal of 1721136215545 is 5455126311271.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 371198966121 + 1349937249424 = 609261^2 + 1161868^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721136215545 - 2⁷ = 1721136215417 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 172113621550 + ... + 172113621559.

It is an arithmetic number, because the mean of its divisors is an integer number (516340864665).

Almost surely, 2^{1721136215545} is an apocalyptic number.

It is an amenable number.

1721136215545 is a deficient number, since it is larger than the sum of its proper divisors (344227243115).

1721136215545 is an equidigital number, since it uses as much as digits as its factorization.

1721136215545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344227243114.

The product of its digits is 252000, while the sum is 43.

The spelling of 1721136215545 in words is "one trillion, seven hundred twenty-one billion, one hundred thirty-six million, two hundred fifteen thousand, five hundred forty-five".