71971421 has 4 divisors (see below), whose sum is σ = 76205052. Its totient is φ = 67737792.

The previous prime is 71971409. The next prime is 71971423. The reversal of 71971421 is 12417917.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12417917 = 47 ⋅264211.

It can be written as a sum of positive squares in 2 ways, for example, as 29539225 + 42432196 = 5435^2 + 6514^2 .

It is not a de Polignac number, because 71971421 - 2¹⁰ = 71970397 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 (71971423) 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, 2116790 + ... + 2116823.

It is an arithmetic number, because the mean of its divisors is an integer number (19051263).

Almost surely, 2^71971421 is an apocalyptic number.

It is an amenable number.

71971421 is a deficient number, since it is larger than the sum of its proper divisors (4233631).

71971421 is a wasteful number, since it uses less digits than its factorization.

71971421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4233630.

The product of its digits is 3528, while the sum is 32.

The square root of 71971421 is about 8483.5971733693. The cubic root of 71971421 is about 415.9617140708.

The spelling of 71971421 in words is "seventy-one million, nine hundred seventy-one thousand, four hundred twenty-one".