261311223540 has 48 divisors (see below), whose sum is σ = 736935272640. Its totient is φ = 69181674240.

The previous prime is 261311223539. The next prime is 261311223541. The reversal of 261311223540 is 45322113162.

It is an interprime number because it is at equal distance from previous prime (261311223539) and next prime (261311223541).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 261311223498 and 261311223507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261311223541) 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, 15657801 + ... + 15674480.

It is an arithmetic number, because the mean of its divisors is an integer number (15352818180).

Almost surely, 2^261311223540 is an apocalyptic number.

261311223540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261311223540 is an abundant number, since it is smaller than the sum of its proper divisors (475624049100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261311223540 is a wasteful number, since it uses less digits than its factorization.

261311223540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31332432 (or 31332430 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The spelling of 261311223540 in words is "two hundred sixty-one billion, three hundred eleven million, two hundred twenty-three thousand, five hundred forty".