1309531861 has 16 divisors (see below), whose sum is σ = 1470403008. Its totient is φ = 1155772800.

The previous prime is 1309531837. The next prime is 1309531877. The reversal of 1309531861 is 1681359031.

It is a 4-Lehmer number, since φ(1309531861) divides (1309531861-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 1309531861 - 2⁷ = 1309531733 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1309531861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1309531831) 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, 196561 + ... + 203113.

It is an arithmetic number, because the mean of its divisors is an integer number (91900188).

It is a Poulet number, since it divides 2^1309531860-1.

Almost surely, 2^1309531861 is an apocalyptic number.

1309531861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1309531861 is a deficient number, since it is larger than the sum of its proper divisors (160871147).

1309531861 is a wasteful number, since it uses less digits than its factorization.

1309531861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7092.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 1309531861 is about 36187.4544697468. The cubic root of 1309531861 is about 1094.0538273388.

The spelling of 1309531861 in words is "one billion, three hundred nine million, five hundred thirty-one thousand, eight hundred sixty-one".