81247428 has 24 divisors (see below), whose sum is σ = 210641760. Its totient is φ = 27082440.

The previous prime is 81247427. The next prime is 81247429. The reversal of 81247428 is 82474218.

It is an interprime number because it is at equal distance from previous prime (81247427) and next prime (81247429).

It is a super-2 number, since 2×81247428² = 13202289113230368, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 81247392 and 81247401.

It is not an unprimeable number, because it can be changed into a prime (81247423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 376038 + ... + 376253.

It is an arithmetic number, because the mean of its divisors is an integer number (8776740).

Almost surely, 2^81247428 is an apocalyptic number.

It is an amenable number.

81247428 is an abundant number, since it is smaller than the sum of its proper divisors (129394332).

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

81247428 is a wasteful number, since it uses less digits than its factorization.

81247428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 752304 (or 752296 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 81247428 is about 9013.7355186404. The cubic root of 81247428 is about 433.1149824336.

The spelling of 81247428 in words is "eighty-one million, two hundred forty-seven thousand, four hundred twenty-eight".