81021319 has 4 divisors (see below), whose sum is σ = 81040120. Its totient is φ = 81002520.

The previous prime is 81021271. The next prime is 81021407. The reversal of 81021319 is 91312018.

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

It is a cyclic number.

It is not a de Polignac number, because 81021319 - 2⁷ = 81021191 is a prime.

It is a super-2 number, since 2×81021319² = 13128908264999522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81021293 and 81021302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81021119) 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, 637 + ... + 12745.

It is an arithmetic number, because the mean of its divisors is an integer number (20260030).

Almost surely, 2^81021319 is an apocalyptic number.

81021319 is a deficient number, since it is larger than the sum of its proper divisors (18801).

81021319 is a wasteful number, since it uses less digits than its factorization.

81021319 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18800.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 81021319 is about 9001.1843109671. The cubic root of 81021319 is about 432.7128274150.

The spelling of 81021319 in words is "eighty-one million, twenty-one thousand, three hundred nineteen".