81900590 has 16 divisors (see below), whose sum is σ = 147958272. Its totient is φ = 32640864.

The previous prime is 81900569. The next prime is 81900593. The reversal of 81900590 is 9500918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81900593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12014 + ... + 17553.

It is an arithmetic number, because the mean of its divisors is an integer number (9247392).

Almost surely, 2^81900590 is an apocalyptic number.

81900590 is a deficient number, since it is larger than the sum of its proper divisors (66057682).

81900590 is a wasteful number, since it uses less digits than its factorization.

81900590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29851.

The product of its (nonzero) digits is 3240, while the sum is 32.

The square root of 81900590 is about 9049.8944745229. The cubic root of 81900590 is about 434.2725146137.

The spelling of 81900590 in words is "eighty-one million, nine hundred thousand, five hundred ninety".