71155421 has 4 divisors (see below), whose sum is σ = 75341052. Its totient is φ = 66969792.

The previous prime is 71155391. The next prime is 71155453. The reversal of 71155421 is 12455117.

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 36168196 + 34987225 = 6014^2 + 5915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71155421 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 (71155481) 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, 2092790 + ... + 2092823.

It is an arithmetic number, because the mean of its divisors is an integer number (18835263).

Almost surely, 2^71155421 is an apocalyptic number.

It is an amenable number.

71155421 is a deficient number, since it is larger than the sum of its proper divisors (4185631).

71155421 is a wasteful number, since it uses less digits than its factorization.

71155421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4185630.

The product of its digits is 1400, while the sum is 26.

The square root of 71155421 is about 8435.3672711981. The cubic root of 71155421 is about 414.3837002982.

The spelling of 71155421 in words is "seventy-one million, one hundred fifty-five thousand, four hundred twenty-one".