261538628 has 12 divisors (see below), whose sum is σ = 492899820. Its totient is φ = 120710112.

The previous prime is 261538621. The next prime is 261538643. The reversal of 261538628 is 826835162.

261538628 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 175085824 + 86452804 = 13232^2 + 9298^2 .

It is a super-2 number, since 2×261538628² = 136804907872244768, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261538621) 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, 2514743 + ... + 2514846.

It is an arithmetic number, because the mean of its divisors is an integer number (41074985).

Almost surely, 2^261538628 is an apocalyptic number.

It is an amenable number.

261538628 is a deficient number, since it is larger than the sum of its proper divisors (231361192).

261538628 is a wasteful number, since it uses less digits than its factorization.

261538628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5029606 (or 5029604 counting only the distinct ones).

The product of its digits is 138240, while the sum is 41.

The square root of 261538628 is about 16172.1559478011. The cubic root of 261538628 is about 639.5069672883.

The spelling of 261538628 in words is "two hundred sixty-one million, five hundred thirty-eight thousand, six hundred twenty-eight".