21121657211 has 16 divisors (see below), whose sum is σ = 23510323200. Its totient is φ = 18892180800.

The previous prime is 21121657201. The next prime is 21121657213. The reversal of 21121657211 is 11275612112.

It is a cyclic number.

It is not a de Polignac number, because 21121657211 - 2¹⁰ = 21121656187 is a prime.

It is a super-2 number, since 2×21121657211² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121657213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 413171 + ... + 461468.

It is an arithmetic number, because the mean of its divisors is an integer number (1469395200).

Almost surely, 2^21121657211 is an apocalyptic number.

21121657211 is a deficient number, since it is larger than the sum of its proper divisors (2388665989).

21121657211 is a wasteful number, since it uses less digits than its factorization.

21121657211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874730.

The product of its digits is 1680, while the sum is 29.

The spelling of 21121657211 in words is "twenty-one billion, one hundred twenty-one million, six hundred fifty-seven thousand, two hundred eleven".