261057021 has 4 divisors (see below), whose sum is σ = 348076032. Its totient is φ = 174038012.

The previous prime is 261056977. The next prime is 261057047. The reversal of 261057021 is 120750162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261057021 - 2⁷ = 261056893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261056982 and 261057000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261057221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43509501 + ... + 43509506.

It is an arithmetic number, because the mean of its divisors is an integer number (87019008).

Almost surely, 2^261057021 is an apocalyptic number.

It is an amenable number.

261057021 is a deficient number, since it is larger than the sum of its proper divisors (87019011).

261057021 is an equidigital number, since it uses as much as digits as its factorization.

261057021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87019010.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 261057021 is about 16157.2590806733. The cubic root of 261057021 is about 639.1141887572.

The spelling of 261057021 in words is "two hundred sixty-one million, fifty-seven thousand, twenty-one".