1491581641 has 9 divisors (see below), whose sum is σ = 1639974189. Its totient is φ = 1355597100.

The previous prime is 1491581593. The next prime is 1491581669. The reversal of 1491581641 is 1461851941.

The square root of 1491581641 is 38621.

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

It is a de Polignac number, because none of the positive numbers 2^k-1491581641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1491581594 and 1491581603.

It is not an unprimeable number, because it can be changed into a prime (1491581941) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 423076 + ... + 426586.

Almost surely, 2^1491581641 is an apocalyptic number.

1491581641 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1491581641 is the 38621-st square number.

1491581641 is the 19311-st centered octagonal number.

It is an amenable number.

1491581641 is a deficient number, since it is larger than the sum of its proper divisors (148392548).

1491581641 is an frugal number, since it uses more digits than its factorization.

1491581641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7044 (or 3522 counting only the distinct ones).

The product of its digits is 34560, while the sum is 40.

The cubic root of 1491581641 is about 1142.5687537689.

The spelling of 1491581641 in words is "one billion, four hundred ninety-one million, five hundred eighty-one thousand, six hundred forty-one".