81621471 has 8 divisors (see below), whose sum is σ = 115230384. Its totient is φ = 51213440.

The previous prime is 81621467. The next prime is 81621479. The reversal of 81621471 is 17412618.

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 81621471 - 2² = 81621467 is a prime.

It is a super-3 number, since 3×81621471³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81621479) 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, 800160 + ... + 800261.

It is an arithmetic number, because the mean of its divisors is an integer number (14403798).

Almost surely, 2^81621471 is an apocalyptic number.

81621471 is a deficient number, since it is larger than the sum of its proper divisors (33608913).

81621471 is a wasteful number, since it uses less digits than its factorization.

81621471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1600441.

The product of its digits is 2688, while the sum is 30.

The square root of 81621471 is about 9034.4601941677. The cubic root of 81621471 is about 433.7786163770.

The spelling of 81621471 in words is "eighty-one million, six hundred twenty-one thousand, four hundred seventy-one".