81601252021 has 8 divisors (see below), whose sum is σ = 81666131040. Its totient is φ = 81536403312.

The previous prime is 81601251973. The next prime is 81601252027. The reversal of 81601252021 is 12025210618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81601252021 - 2¹¹ = 81601249973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81601252027) 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, 9171451 + ... + 9180343.

It is an arithmetic number, because the mean of its divisors is an integer number (10208266380).

Almost surely, 2^81601252021 is an apocalyptic number.

It is an amenable number.

81601252021 is a deficient number, since it is larger than the sum of its proper divisors (64879019).

81601252021 is a wasteful number, since it uses less digits than its factorization.

81601252021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15155.

The product of its (nonzero) digits is 1920, while the sum is 28.

Adding to 81601252021 its reverse (12025210618), we get a palindrome (93626462639).

The spelling of 81601252021 in words is "eighty-one billion, six hundred one million, two hundred fifty-two thousand, twenty-one".