81532621 has 2 divisors, whose sum is σ = 81532622. Its totient is φ = 81532620.

The previous prime is 81532597. The next prime is 81532669. The reversal of 81532621 is 12623518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61011721 + 20520900 = 7811^2 + 4530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81532621 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81532621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81532681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40766310 + 40766311.

It is an arithmetic number, because the mean of its divisors is an integer number (40766311).

Almost surely, 2^81532621 is an apocalyptic number.

It is an amenable number.

81532621 is a deficient number, since it is larger than the sum of its proper divisors (1).

81532621 is an equidigital number, since it uses as much as digits as its factorization.

81532621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 28.

The square root of 81532621 is about 9029.5415719736. The cubic root of 81532621 is about 433.6211609800.

The spelling of 81532621 in words is "eighty-one million, five hundred thirty-two thousand, six hundred twenty-one".