261542811420 has 288 divisors, whose sum is σ = 917346306240. Its totient is φ = 59611668480.

The previous prime is 261542811419. The next prime is 261542811427. The reversal of 261542811420 is 24118245162.

261542811420 is a `hidden beast` number, since 2 + 6 + 1 + 542 + 81 + 14 + 20 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261542811427) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 36786826 + ... + 36793934.

It is an arithmetic number, because the mean of its divisors is an integer number (3185230230).

Almost surely, 2^261542811420 is an apocalyptic number.

261542811420 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 261542811420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (458673153120).

261542811420 is an abundant number, since it is smaller than the sum of its proper divisors (655803494820).

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

261542811420 is a wasteful number, since it uses less digits than its factorization.

261542811420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8245 (or 8240 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The spelling of 261542811420 in words is "two hundred sixty-one billion, five hundred forty-two million, eight hundred eleven thousand, four hundred twenty".