21254556261 has 32 divisors (see below), whose sum is σ = 29094208000. Its totient is φ = 13797812160.

The previous prime is 21254556233. The next prime is 21254556263. The reversal of 21254556261 is 16265545212.

It is not a de Polignac number, because 21254556261 - 2¹¹ = 21254554213 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21254556263) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12509190 + ... + 12510888.

It is an arithmetic number, because the mean of its divisors is an integer number (909194000).

Almost surely, 2^21254556261 is an apocalyptic number.

It is an amenable number.

21254556261 is a deficient number, since it is larger than the sum of its proper divisors (7839651739).

21254556261 is a wasteful number, since it uses less digits than its factorization.

21254556261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2449.

The product of its digits is 144000, while the sum is 39.

The spelling of 21254556261 in words is "twenty-one billion, two hundred fifty-four million, five hundred fifty-six thousand, two hundred sixty-one".