81266220 has 96 divisors (see below), whose sum is σ = 288960000. Its totient is φ = 18574272.

The previous prime is 81266219. The next prime is 81266233. The reversal of 81266220 is 2266218.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6970 + ... + 14529.

It is an arithmetic number, because the mean of its divisors is an integer number (3010000).

Almost surely, 2^81266220 is an apocalyptic number.

It is an amenable number.

81266220 is an abundant number, since it is smaller than the sum of its proper divisors (207693780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81266220 is a wasteful number, since it uses less digits than its factorization.

81266220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21524 (or 21516 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 81266220 is about 9014.7778674796. Note that the first 3 decimals coincide. The cubic root of 81266220 is about 433.1483720826.

The spelling of 81266220 in words is "eighty-one million, two hundred sixty-six thousand, two hundred twenty".