81792780 has 144 divisors (see below), whose sum is σ = 250659360. Its totient is φ = 19914752.

The previous prime is 81792779. The next prime is 81792791. The reversal of 81792780 is 8729718.

81792780 = T₁₃₁₁ + T₁₃₁₂ + ... + T₁₃₉₉.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 918976 + ... + 919064.

It is an arithmetic number, because the mean of its divisors is an integer number (1740690).

Almost surely, 2^81792780 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 81792780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125329680).

81792780 is an abundant number, since it is smaller than the sum of its proper divisors (168866580).

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

81792780 is a wasteful number, since it uses less digits than its factorization.

81792780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 169 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 81792780 is about 9043.9360899998. The cubic root of 81792780 is about 434.0818791200.

The spelling of 81792780 in words is "eighty-one million, seven hundred ninety-two thousand, seven hundred eighty".