81561452 has 36 divisors (see below), whose sum is σ = 172181520. Its totient is φ = 33111072.

The previous prime is 81561421. The next prime is 81561457. The reversal of 81561452 is 25416518.

It is not an unprimeable number, because it can be changed into a prime (81561457) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6074 + ... + 14142.

It is an arithmetic number, because the mean of its divisors is an integer number (4782820).

Almost surely, 2^81561452 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81561452, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86090760).

81561452 is an abundant number, since it is smaller than the sum of its proper divisors (90620068).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81561452 is a wasteful number, since it uses less digits than its factorization.

81561452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8118 (or 8097 counting only the distinct ones).

The product of its digits is 9600, while the sum is 32.

The square root of 81561452 is about 9031.1379127993. The cubic root of 81561452 is about 433.6722663258.

The spelling of 81561452 in words is "eighty-one million, five hundred sixty-one thousand, four hundred fifty-two".