1491748806581 has 32 divisors (see below), whose sum is σ = 1678372824960. Its totient is φ = 1313940614400.

The previous prime is 1491748806529. The next prime is 1491748806623. The reversal of 1491748806581 is 1856088471941.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1491748806581 is a prime.

It is a super-2 number, since 2×1491748806581² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1491748803581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 277222511 + ... + 277227891.

It is an arithmetic number, because the mean of its divisors is an integer number (52449150780).

Almost surely, 2^{1491748806581} is an apocalyptic number.

1491748806581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1491748806581 is a deficient number, since it is larger than the sum of its proper divisors (186624018379).

1491748806581 is a wasteful number, since it uses less digits than its factorization.

1491748806581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8165.

The product of its (nonzero) digits is 15482880, while the sum is 62.

The spelling of 1491748806581 in words is "one trillion, four hundred ninety-one billion, seven hundred forty-eight million, eight hundred six thousand, five hundred eighty-one".