81501420 has 384 divisors, whose sum is σ = 325140480. Its totient is φ = 14699520.

The previous prime is 81501401. The next prime is 81501421. The reversal of 81501420 is 2410518.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (81501421) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1381351 + ... + 1381409.

It is an arithmetic number, because the mean of its divisors is an integer number (846720).

Almost surely, 2^81501420 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 81501420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162570240).

81501420 is an abundant number, since it is smaller than the sum of its proper divisors (243639060).

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

81501420 is a wasteful number, since it uses less digits than its factorization.

81501420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 81501420 is about 9027.8136888175. The cubic root of 81501420 is about 433.5658410362.

Adding to 81501420 its reverse (2410518), we get a palindrome (83911938).

It can be divided in two parts, 81 and 501420, that added together give a triangular number (501501 = T₁₀₀₁).

The spelling of 81501420 in words is "eighty-one million, five hundred one thousand, four hundred twenty".