81921466 has 16 divisors (see below), whose sum is σ = 134320608. Its totient is φ = 37162800.

The previous prime is 81921439. The next prime is 81921467. The reversal of 81921466 is 66412918.

It is a happy number.

It is a super-2 number, since 2×81921466² = 13422253183178312, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81921467) 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, 8461 + ... + 15343.

It is an arithmetic number, because the mean of its divisors is an integer number (8395038).

Almost surely, 2^81921466 is an apocalyptic number.

81921466 is a deficient number, since it is larger than the sum of its proper divisors (52399142).

81921466 is a wasteful number, since it uses less digits than its factorization.

81921466 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7437.

The product of its digits is 20736, while the sum is 37.

The square root of 81921466 is about 9051.0477846490. The cubic root of 81921466 is about 434.3094093534.

The spelling of 81921466 in words is "eighty-one million, nine hundred twenty-one thousand, four hundred sixty-six".