261399420 has 96 divisors (see below), whose sum is σ = 816076800. Its totient is φ = 69463872.

The previous prime is 261399419. The next prime is 261399427. The reversal of 261399420 is 24993162.

261399420 is a `hidden beast` number, since 261 + 399 + 4 + 2 + 0 = 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 (261399427) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 197521 + ... + 198839.

It is an arithmetic number, because the mean of its divisors is an integer number (8500800).

Almost surely, 2^261399420 is an apocalyptic number.

261399420 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 261399420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (408038400).

261399420 is an abundant number, since it is smaller than the sum of its proper divisors (554677380).

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

261399420 is a wasteful number, since it uses less digits than its factorization.

261399420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1704 (or 1696 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 261399420 is about 16167.8514342506. The cubic root of 261399420 is about 639.3934846437.

The spelling of 261399420 in words is "two hundred sixty-one million, three hundred ninety-nine thousand, four hundred twenty".