81553730 has 16 divisors (see below), whose sum is σ = 146902464. Its totient is φ = 32598000.

The previous prime is 81553727. The next prime is 81553733. The reversal of 81553730 is 3735518.

It is an interprime number because it is at equal distance from previous prime (81553727) and next prime (81553733).

It is not an unprimeable number, because it can be changed into a prime (81553733) 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, 20699 + ... + 24321.

It is an arithmetic number, because the mean of its divisors is an integer number (9181404).

Almost surely, 2^81553730 is an apocalyptic number.

81553730 is a deficient number, since it is larger than the sum of its proper divisors (65348734).

81553730 is a wasteful number, since it uses less digits than its factorization.

81553730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5881.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 81553730 is about 9030.7103818028. The cubic root of 81553730 is about 433.6585796195.

It can be divided in two parts, 815 and 53730, that added together give a palindrome (54545).

The spelling of 81553730 in words is "eighty-one million, five hundred fifty-three thousand, seven hundred thirty".