81428616 has 24 divisors (see below), whose sum is σ = 220536030. Its totient is φ = 27142848.

The previous prime is 81428609. The next prime is 81428621. The reversal of 81428616 is 61682418.

81428616 is a `hidden beast` number, since 8 + 14 + 28 + 616 = 666.

It can be written as a sum of positive squares in only one way, i.e., 76632516 + 4796100 = 8754^2 + 2190^2 .

It is a tau number, because it is divible by the number of its divisors (24).

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

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 565405 + ... + 565548.

Almost surely, 2^81428616 is an apocalyptic number.

It is an amenable number.

81428616 is an abundant number, since it is smaller than the sum of its proper divisors (139107414).

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

81428616 is a wasteful number, since it uses less digits than its factorization.

81428616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1130965 (or 1130958 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 81428616 is about 9023.7805824388. The cubic root of 81428616 is about 433.4367032817.

The spelling of 81428616 in words is "eighty-one million, four hundred twenty-eight thousand, six hundred sixteen".