261611263620 has 1152 divisors, whose sum is σ = 1053071953920. Its totient is φ = 53508833280.

The previous prime is 261611263619. The next prime is 261611263649. The reversal of 261611263620 is 26362116162.

261611263620 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 1 + 1 + 26 + 3 + 620 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 1017942532 + ... + 1017942788.

It is an arithmetic number, because the mean of its divisors is an integer number (914124960).

Almost surely, 2^261611263620 is an apocalyptic number.

261611263620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261611263620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (526535976960).

261611263620 is an abundant number, since it is smaller than the sum of its proper divisors (791460690300).

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

261611263620 is a wasteful number, since it uses less digits than its factorization.

261611263620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410 (or 395 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

Adding to 261611263620 its reverse (26362116162), we get a palindrome (287973379782).

The spelling of 261611263620 in words is "two hundred sixty-one billion, six hundred eleven million, two hundred sixty-three thousand, six hundred twenty".