261226661501 has 4 divisors (see below), whose sum is σ = 281321020092. Its totient is φ = 241132302912.

The previous prime is 261226661497. The next prime is 261226661503. The reversal of 261226661501 is 105166622162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 161402259001 + 99824402500 = 401749^2 + 315950^2 .

It is a cyclic number.

It is not a de Polignac number, because 261226661501 - 2² = 261226661497 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261226661503) 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, 10047179276 + ... + 10047179301.

It is an arithmetic number, because the mean of its divisors is an integer number (70330255023).

Almost surely, 2^261226661501 is an apocalyptic number.

It is an amenable number.

261226661501 is a deficient number, since it is larger than the sum of its proper divisors (20094358591).

261226661501 is a wasteful number, since it uses less digits than its factorization.

261226661501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20094358590.

The product of its (nonzero) digits is 51840, while the sum is 38.

The spelling of 261226661501 in words is "two hundred sixty-one billion, two hundred twenty-six million, six hundred sixty-one thousand, five hundred one".