81921356 has 18 divisors (see below), whose sum is σ = 157581060. Its totient is φ = 37236760.

The previous prime is 81921337. The next prime is 81921361. The reversal of 81921356 is 65312918.

It is a super-2 number, since 2×81921356² = 13422217137757472, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 84146 + ... + 85113.

Almost surely, 2^81921356 is an apocalyptic number.

It is an amenable number.

81921356 is a deficient number, since it is larger than the sum of its proper divisors (75659704).

81921356 is a wasteful number, since it uses less digits than its factorization.

81921356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169285 (or 169272 counting only the distinct ones).

The product of its digits is 12960, while the sum is 35.

The square root of 81921356 is about 9051.0417080025. The cubic root of 81921356 is about 434.3092149638.

The spelling of 81921356 in words is "eighty-one million, nine hundred twenty-one thousand, three hundred fifty-six".