81428782 has 4 divisors (see below), whose sum is σ = 122143176. Its totient is φ = 40714390.

The previous prime is 81428779. The next prime is 81428783. The reversal of 81428782 is 28782418.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81428783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20357194 + ... + 20357197.

It is an arithmetic number, because the mean of its divisors is an integer number (30535794).

Almost surely, 2^81428782 is an apocalyptic number.

81428782 is a deficient number, since it is larger than the sum of its proper divisors (40714394).

81428782 is a wasteful number, since it uses less digits than its factorization.

81428782 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40714393.

The product of its digits is 57344, while the sum is 40.

The square root of 81428782 is about 9023.7897803528. The cubic root of 81428782 is about 433.4369978155.

The spelling of 81428782 in words is "eighty-one million, four hundred twenty-eight thousand, seven hundred eighty-two".