81653634001 has 9 divisors (see below), whose sum is σ = 83931001371. Its totient is φ = 79436491992.

The previous prime is 81653633989. The next prime is 81653634011. The reversal of 81653634001 is 10043635618.

The square root of 81653634001 is 285751.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 73064793025 + 8588840976 = 270305^2 + 92676^2 .

It is not a de Polignac number, because 81653634001 - 2⁹ = 81653633489 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81653634011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 10568926 + ... + 10576648.

It is an arithmetic number, because the mean of its divisors is an integer number (9325666819).

Almost surely, 2^81653634001 is an apocalyptic number.

81653634001 is the 285751-st square number.

81653634001 is the 142876-th centered octagonal number.

It is an amenable number.

81653634001 is a deficient number, since it is larger than the sum of its proper divisors (2277367370).

81653634001 is an frugal number, since it uses more digits than its factorization.

81653634001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15520 (or 7760 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 81653634001 in words is "eighty-one billion, six hundred fifty-three million, six hundred thirty-four thousand, one".