81213450 has 48 divisors (see below), whose sum is σ = 202995936. Its totient is φ = 21486400.

The previous prime is 81213443. The next prime is 81213491. The reversal of 81213450 is 5431218.

It is a self number, because there is not a number n which added to its sum of digits gives 81213450.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17584 + ... + 21716.

It is an arithmetic number, because the mean of its divisors is an integer number (4229082).

Almost surely, 2^81213450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81213450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101497968).

81213450 is an abundant number, since it is smaller than the sum of its proper divisors (121782486).

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

81213450 is a wasteful number, since it uses less digits than its factorization.

81213450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4279 (or 4274 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 81213450 is about 9011.8505313837. The cubic root of 81213450 is about 433.0545972078.

Adding to 81213450 its reverse (5431218), we get a palindrome (86644668).

It can be divided in two parts, 81 and 213450, that added together give a triangular number (213531 = T₆₅₃).

The spelling of 81213450 in words is "eighty-one million, two hundred thirteen thousand, four hundred fifty".