81052921 has 4 divisors (see below), whose sum is σ = 81193972. Its totient is φ = 80911872.

The previous prime is 81052919. The next prime is 81052931. The reversal of 81052921 is 12925018.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 61152400 + 19900521 = 7820^2 + 4461^2 .

It is a cyclic number.

It is not a de Polignac number, because 81052921 - 2¹ = 81052919 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81052921.

It is not an unprimeable number, because it can be changed into a prime (81052931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69660 + ... + 70813.

It is an arithmetic number, because the mean of its divisors is an integer number (20298493).

Almost surely, 2^81052921 is an apocalyptic number.

It is an amenable number.

81052921 is a deficient number, since it is larger than the sum of its proper divisors (141051).

81052921 is a wasteful number, since it uses less digits than its factorization.

81052921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141050.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 81052921 is about 9002.9395754942. The cubic root of 81052921 is about 432.7690793308.

Adding to 81052921 its reverse (12925018), we get a palindrome (93977939).

It can be divided in two parts, 8105 and 2921, that added together give a triangular number (11026 = T₁₄₈).

The spelling of 81052921 in words is "eighty-one million, fifty-two thousand, nine hundred twenty-one".