71987921 has 8 divisors (see below), whose sum is σ = 74508288. Its totient is φ = 69480000.

The previous prime is 71987887. The next prime is 71987957. The reversal of 71987921 is 12978917.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 71987921 - 2⁶ = 71987857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71987821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9536 + ... + 15326.

It is an arithmetic number, because the mean of its divisors is an integer number (9313536).

Almost surely, 2^71987921 is an apocalyptic number.

It is an amenable number.

71987921 is a deficient number, since it is larger than the sum of its proper divisors (2520367).

71987921 is a wasteful number, since it uses less digits than its factorization.

71987921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6223.

The product of its digits is 63504, while the sum is 44.

The square root of 71987921 is about 8484.5695824833. The cubic root of 71987921 is about 415.9934991125.

The spelling of 71987921 in words is "seventy-one million, nine hundred eighty-seven thousand, nine hundred twenty-one".