1261540819 has 12 divisors (see below), whose sum is σ = 1600917048. Its totient is φ = 983018400.

The previous prime is 1261540801. The next prime is 1261540829. The reversal of 1261540819 is 9180451621.

It is a de Polignac number, because none of the positive numbers 2^k-1261540819 is a prime.

It is a super-2 number, since 2×1261540819² = 3182970476006381522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261540829) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1169722 + ... + 1170799.

It is an arithmetic number, because the mean of its divisors is an integer number (133409754).

Almost surely, 2^1261540819 is an apocalyptic number.

1261540819 is a deficient number, since it is larger than the sum of its proper divisors (339376229).

1261540819 is a wasteful number, since it uses less digits than its factorization.

1261540819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2340546 (or 2340539 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 1261540819 is about 35518.1758962929. The cubic root of 1261540819 is about 1080.5223864602.

The spelling of 1261540819 in words is "one billion, two hundred sixty-one million, five hundred forty thousand, eight hundred nineteen".