81220215 has 8 divisors (see below), whose sum is σ = 129952368. Its totient is φ = 43317440.

The previous prime is 81220211. The next prime is 81220247. The reversal of 81220215 is 51202218.

It is a happy number.

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

It is not a de Polignac number, because 81220215 - 2² = 81220211 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81220191 and 81220200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81220211) 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, 2707326 + ... + 2707355.

It is an arithmetic number, because the mean of its divisors is an integer number (16244046).

Almost surely, 2^81220215 is an apocalyptic number.

81220215 is a deficient number, since it is larger than the sum of its proper divisors (48732153).

81220215 is a wasteful number, since it uses less digits than its factorization.

81220215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5414689.

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

The square root of 81220215 is about 9012.2258626823. The cubic root of 81220215 is about 433.0666212138.

The spelling of 81220215 in words is "eighty-one million, two hundred twenty thousand, two hundred fifteen".