261721152 has 336 divisors, whose sum is σ = 979871040. Its totient is φ = 67737600.

The previous prime is 261721139. The next prime is 261721153. The reversal of 261721152 is 251127162.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×261721152² = 136995922808414208, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (261721153) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 931252 + ... + 931532.

Almost surely, 2^261721152 is an apocalyptic number.

261721152 is a gapful number since it is divisible by the number (22) 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 261721152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (489935520).

261721152 is an abundant number, since it is smaller than the sum of its proper divisors (718149888).

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

261721152 is a wasteful number, since it uses less digits than its factorization.

261721152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 304 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 261721152 is about 16177.7981196453. The cubic root of 261721152 is about 639.6557002275.

The spelling of 261721152 in words is "two hundred sixty-one million, seven hundred twenty-one thousand, one hundred fifty-two".