81617472 has 42 divisors (see below), whose sum is σ = 233943398. Its totient is φ = 27205632.

The previous prime is 81617467. The next prime is 81617477. The reversal of 81617472 is 27471618.

It is an interprime number because it is at equal distance from previous prime (81617467) and next prime (81617477).

It can be written as a sum of positive squares in only one way, i.e., 70963776 + 10653696 = 8424^2 + 3264^2 .

It is a super-2 number, since 2×81617472² = 13322823471341568, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (81617477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 70273 + ... + 71424.

Almost surely, 2^81617472 is an apocalyptic number.

It is an amenable number.

81617472 is an abundant number, since it is smaller than the sum of its proper divisors (152325926).

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

81617472 is a wasteful number, since it uses less digits than its factorization.

81617472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141715 (or 141702 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 81617472 is about 9034.2388722017. The cubic root of 81617472 is about 433.7715320114.

The spelling of 81617472 in words is "eighty-one million, six hundred seventeen thousand, four hundred seventy-two".