81377280 has 144 divisors (see below), whose sum is σ = 282358440. Its totient is φ = 21676032.

The previous prime is 81377279. The next prime is 81377293. The reversal of 81377280 is 8277318.

81377280 is a `hidden beast` number, since 8 + 1 + 377 + 280 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91719 + ... + 92601.

Almost surely, 2^81377280 is an apocalyptic number.

81377280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81377280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (141179220).

81377280 is an abundant number, since it is smaller than the sum of its proper divisors (200981160).

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

81377280 is a wasteful number, since it uses less digits than its factorization.

81377280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 916 (or 893 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 81377280 is about 9020.9356499201. The cubic root of 81377280 is about 433.3455986009.

The spelling of 81377280 in words is "eighty-one million, three hundred seventy-seven thousand, two hundred eighty".