261999902421 has 24 divisors (see below), whose sum is σ = 378876642144. Its totient is φ = 174467196000.

The previous prime is 261999902399. The next prime is 261999902447. The reversal of 261999902421 is 124209999162.

261999902421 is a `hidden beast` number, since 26 + 199 + 9 + 9 + 0 + 2 + 421 = 666.

261999902421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261999902421 - 2⁶ = 261999902357 is a prime.

It is a super-2 number, since 2×261999902421² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261999902491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36199215 + ... + 36206451.

It is an arithmetic number, because the mean of its divisors is an integer number (15786526756).

Almost surely, 2^261999902421 is an apocalyptic number.

It is an amenable number.

261999902421 is a deficient number, since it is larger than the sum of its proper divisors (116876739723).

261999902421 is a wasteful number, since it uses less digits than its factorization.

261999902421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11281 (or 11278 counting only the distinct ones).

The product of its (nonzero) digits is 1259712, while the sum is 54.

The spelling of 261999902421 in words is "two hundred sixty-one billion, nine hundred ninety-nine million, nine hundred two thousand, four hundred twenty-one".