81042501 has 32 divisors (see below), whose sum is σ = 118091520. Its totient is φ = 49280000.

The previous prime is 81042491. The next prime is 81042503. The reversal of 81042501 is 10524018.

It is a 5-Lehmer number, since φ(81042501) divides (81042501-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 81042501 - 2⁷ = 81042373 is a prime.

It is a Curzon number.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81042503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 201901 + ... + 202301.

It is an arithmetic number, because the mean of its divisors is an integer number (3690360).

Almost surely, 2^81042501 is an apocalyptic number.

It is an amenable number.

81042501 is a deficient number, since it is larger than the sum of its proper divisors (37049019).

81042501 is a wasteful number, since it uses less digits than its factorization.

81042501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 557.

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 81042501 is about 9002.3608570197. The cubic root of 81042501 is about 432.7505332295.

Adding to 81042501 its reverse (10524018), we get a palindrome (91566519).

The spelling of 81042501 in words is "eighty-one million, forty-two thousand, five hundred one".