261721152001 has 2 divisors, whose sum is σ = 261721152002. Its totient is φ = 261721152000.

The previous prime is 261721151969. The next prime is 261721152023. The reversal of 261721152001 is 100251127162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219657192976 + 42063959025 = 468676^2 + 205095^2 .

It is a cyclic number.

It is not a de Polignac number, because 261721152001 - 2⁵ = 261721151969 is a prime.

It is a super-2 number, since 2×261721152001² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261721152031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130860576000 + 130860576001.

It is an arithmetic number, because the mean of its divisors is an integer number (130860576001).

Almost surely, 2^261721152001 is an apocalyptic number.

It is an amenable number.

261721152001 is a deficient number, since it is larger than the sum of its proper divisors (1).

261721152001 is an equidigital number, since it uses as much as digits as its factorization.

261721152001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 28.

Adding to 261721152001 its reverse (100251127162), we get a palindrome (361972279163).

The spelling of 261721152001 in words is "two hundred sixty-one billion, seven hundred twenty-one million, one hundred fifty-two thousand, one".