21511505105 has 8 divisors (see below), whose sum is σ = 25820563752. Its totient is φ = 17204699008.

The previous prime is 21511505077. The next prime is 21511505117. The reversal of 21511505105 is 50150511512.

It can be written as a sum of positive squares in 4 ways, for example, as 358420624 + 21153084481 = 18932^2 + 145441^2 .

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 21511505105 - 2¹² = 21511501009 is a prime.

It is a super-2 number, since 2×21511505105² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 542054 + ... + 580383.

It is an arithmetic number, because the mean of its divisors is an integer number (3227570469).

Almost surely, 2^21511505105 is an apocalyptic number.

It is an amenable number.

21511505105 is a deficient number, since it is larger than the sum of its proper divisors (4309058647).

21511505105 is a wasteful number, since it uses less digits than its factorization.

21511505105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1126275.

The product of its (nonzero) digits is 1250, while the sum is 26.

The spelling of 21511505105 in words is "twenty-one billion, five hundred eleven million, five hundred five thousand, one hundred five".