261651603 has 16 divisors (see below), whose sum is σ = 375774080. Its totient is φ = 161409024.

The previous prime is 261651589. The next prime is 261651617. The reversal of 261651603 is 306156162.

It is an interprime number because it is at equal distance from previous prime (261651589) and next prime (261651617).

It is not a de Polignac number, because 261651603 - 2⁴ = 261651587 is a prime.

It is a super-2 number, since 2×261651603² = 136923122704939218, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261651653) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50926 + ... + 55827.

It is an arithmetic number, because the mean of its divisors is an integer number (23485880).

Almost surely, 2^261651603 is an apocalyptic number.

261651603 is a deficient number, since it is larger than the sum of its proper divisors (114122477).

261651603 is a wasteful number, since it uses less digits than its factorization.

261651603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106818.

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 261651603 is about 16175.6484568626. The cubic root of 261651603 is about 639.5990351405.

The spelling of 261651603 in words is "two hundred sixty-one million, six hundred fifty-one thousand, six hundred three".