155261071120021 has 4 divisors (see below), whose sum is σ = 156798309448044. Its totient is φ = 153723832792000.

The previous prime is 155261071120013. The next prime is 155261071120037. The reversal of 155261071120021 is 120021170162551.

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 129018134718225 + 26242936401796 = 11358615^2 + 5122786^2 .

It is a cyclic number.

It is not a de Polignac number, because 155261071120021 - 2³ = 155261071120013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155261071120091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 768619163860 + ... + 768619164061.

It is an arithmetic number, because the mean of its divisors is an integer number (39199577362011).

Almost surely, 2^{155261071120021} is an apocalyptic number.

It is an amenable number.

155261071120021 is a deficient number, since it is larger than the sum of its proper divisors (1537238328023).

155261071120021 is a wasteful number, since it uses less digits than its factorization.

155261071120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1537238328022.

The product of its (nonzero) digits is 8400, while the sum is 34.

The spelling of 155261071120021 in words is "one hundred fifty-five trillion, two hundred sixty-one billion, seventy-one million, one hundred twenty thousand, twenty-one".