81485921 has 16 divisors (see below), whose sum is σ = 91272960. Its totient is φ = 72113280.

The previous prime is 81485897. The next prime is 81485933. The reversal of 81485921 is 12958418.

It is a cyclic number.

It is not a de Polignac number, because 81485921 - 2²⁶ = 14377057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81485821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 142925 + ... + 143493.

It is an arithmetic number, because the mean of its divisors is an integer number (5704560).

Almost surely, 2^81485921 is an apocalyptic number.

It is an amenable number.

81485921 is a deficient number, since it is larger than the sum of its proper divisors (9787039).

81485921 is a wasteful number, since it uses less digits than its factorization.

81485921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 904.

The product of its digits is 23040, while the sum is 38.

The square root of 81485921 is about 9026.9552452640. The cubic root of 81485921 is about 433.5383557769.

The spelling of 81485921 in words is "eighty-one million, four hundred eighty-five thousand, nine hundred twenty-one".