865494253261 has 16 divisors (see below), whose sum is σ = 1006449638400. Its totient is φ = 735966270000.

The previous prime is 865494253249. The next prime is 865494253297. The reversal of 865494253261 is 162352494568.

It is a 4-Lehmer number, since φ(865494253261) divides (865494253261-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 865494253261 - 2³¹ = 863346769613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865494253661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26193115 + ... + 26226136.

It is an arithmetic number, because the mean of its divisors is an integer number (62903102400).

Almost surely, 2^865494253261 is an apocalyptic number.

865494253261 is the 416052-nd centered decagonal number.

It is an amenable number.

865494253261 is a deficient number, since it is larger than the sum of its proper divisors (140955385139).

865494253261 is a wasteful number, since it uses less digits than its factorization.

865494253261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52419360.

The product of its digits is 12441600, while the sum is 55.

The spelling of 865494253261 in words is "eight hundred sixty-five billion, four hundred ninety-four million, two hundred fifty-three thousand, two hundred sixty-one".