81641554 has 8 divisors (see below), whose sum is σ = 126685260. Its totient is φ = 39413136.

The previous prime is 81641501. The next prime is 81641557. The reversal of 81641554 is 45514618.

It can be written as a sum of positive squares in 2 ways, for example, as 76475025 + 5166529 = 8745^2 + 2273^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81641557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 703749 + ... + 703864.

Almost surely, 2^81641554 is an apocalyptic number.

81641554 is a deficient number, since it is larger than the sum of its proper divisors (45043706).

81641554 is a wasteful number, since it uses less digits than its factorization.

81641554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1407644.

The product of its digits is 19200, while the sum is 34.

The square root of 81641554 is about 9035.5715923233. The cubic root of 81641554 is about 433.8141906013.

The spelling of 81641554 in words is "eighty-one million, six hundred forty-one thousand, five hundred fifty-four".