81921480 has 32 divisors (see below), whose sum is σ = 245764800. Its totient is φ = 21845696.

The previous prime is 81921467. The next prime is 81921509. The reversal of 81921480 is 8412918.

It is a super-2 number, since 2×81921480² = 13422257770780800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 341220 + ... + 341459.

It is an arithmetic number, because the mean of its divisors is an integer number (7680150).

Almost surely, 2^81921480 is an apocalyptic number.

It is an amenable number.

81921480 is an abundant number, since it is smaller than the sum of its proper divisors (163843320).

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

81921480 is a wasteful number, since it uses less digits than its factorization.

81921480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 682693 (or 682689 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 81921480 is about 9051.0485580401. The cubic root of 81921480 is about 434.3094340939.

The spelling of 81921480 in words is "eighty-one million, nine hundred twenty-one thousand, four hundred eighty".