21126154261 has 8 divisors (see below), whose sum is σ = 21330075800. Its totient is φ = 20922416640.

The previous prime is 21126154253. The next prime is 21126154277. The reversal of 21126154261 is 16245162112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7504930161 + 13621224100 = 86631^2 + 116710^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21126154261 - 2³ = 21126154253 is a prime.

It is a super-2 number, since 2×21126154261² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21126154241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 190705 + ... + 280393.

It is an arithmetic number, because the mean of its divisors is an integer number (2666259475).

Almost surely, 2^21126154261 is an apocalyptic number.

It is an amenable number.

21126154261 is a deficient number, since it is larger than the sum of its proper divisors (203921539).

21126154261 is a wasteful number, since it uses less digits than its factorization.

21126154261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91959.

The product of its digits is 5760, while the sum is 31.

The spelling of 21126154261 in words is "twenty-one billion, one hundred twenty-six million, one hundred fifty-four thousand, two hundred sixty-one".