1491552781 has 4 divisors (see below), whose sum is σ = 1495851552. Its totient is φ = 1487254012.

The previous prime is 1491552779. The next prime is 1491552787. The reversal of 1491552781 is 1872551941.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1491552781 - 2¹ = 1491552779 is a prime.

It is a super-2 number, since 2×1491552781² = 4449459397017667922, which 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 (1491552787) 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, 2148865 + ... + 2149558.

It is an arithmetic number, because the mean of its divisors is an integer number (373962888).

Almost surely, 2^1491552781 is an apocalyptic number.

It is an amenable number.

1491552781 is a deficient number, since it is larger than the sum of its proper divisors (4298771).

1491552781 is an equidigital number, since it uses as much as digits as its factorization.

1491552781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4298770.

The product of its digits is 100800, while the sum is 43.

The square root of 1491552781 is about 38620.6263672665. The cubic root of 1491552781 is about 1142.5613846903.

The spelling of 1491552781 in words is "one billion, four hundred ninety-one million, five hundred fifty-two thousand, seven hundred eighty-one".