81288428 has 12 divisors (see below), whose sum is σ = 153197520. Its totient is φ = 37517712.

The previous prime is 81288413. The next prime is 81288437. The reversal of 81288428 is 82488218.

It is a super-2 number, since 2×81288428² = 13215617053422368, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 781568 + ... + 781671.

It is an arithmetic number, because the mean of its divisors is an integer number (12766460).

Almost surely, 2^81288428 is an apocalyptic number.

It is an amenable number.

81288428 is a deficient number, since it is larger than the sum of its proper divisors (71909092).

81288428 is a wasteful number, since it uses less digits than its factorization.

81288428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1563256 (or 1563254 counting only the distinct ones).

The product of its digits is 65536, while the sum is 41.

The square root of 81288428 is about 9016.0095385930. The cubic root of 81288428 is about 433.1878246495.

The spelling of 81288428 in words is "eighty-one million, two hundred eighty-eight thousand, four hundred twenty-eight".