1261529497811 has 18 divisors (see below), whose sum is σ = 1384599429108. Its totient is φ = 1139899266000.

The previous prime is 1261529497801. The next prime is 1261529497829. The reversal of 1261529497811 is 1187949251621.

It is not a de Polignac number, because 1261529497811 - 2³⁸ = 986651590867 is a prime.

It is a Smith number, since the sum of its digits (56) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261529497801) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 674253206 + ... + 674255076.

It is an arithmetic number, because the mean of its divisors is an integer number (76922190506).

Almost surely, 2^{1261529497811} is an apocalyptic number.

1261529497811 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1261529497811 is a deficient number, since it is larger than the sum of its proper divisors (123069931297).

1261529497811 is an frugal number, since it uses more digits than its factorization.

1261529497811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4115 (or 2063 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 56.

The spelling of 1261529497811 in words is "one trillion, two hundred sixty-one billion, five hundred twenty-nine million, four hundred ninety-seven thousand, eight hundred eleven".