71865421 has 4 divisors (see below), whose sum is σ = 72414144. Its totient is φ = 71316700.

The previous prime is 71865413. The next prime is 71865487. The reversal of 71865421 is 12456817.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 71865421 - 2³ = 71865413 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 (71862421) 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, 274165 + ... + 274426.

It is an arithmetic number, because the mean of its divisors is an integer number (18103536).

Almost surely, 2^71865421 is an apocalyptic number.

It is an amenable number.

71865421 is a deficient number, since it is larger than the sum of its proper divisors (548723).

71865421 is a wasteful number, since it uses less digits than its factorization.

71865421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548722.

The product of its digits is 13440, while the sum is 34.

The square root of 71865421 is about 8477.3475214834. The cubic root of 71865421 is about 415.7574033175.

It can be divided in two parts, 718 and 65421, that multiplied together give a triangular number (46972278 = T₉₆₉₂).

The spelling of 71865421 in words is "seventy-one million, eight hundred sixty-five thousand, four hundred twenty-one".