21053666643 has 16 divisors (see below), whose sum is σ = 29729444256. Its totient is φ = 13207201280.

The previous prime is 21053666633. The next prime is 21053666651. The reversal of 21053666643 is 34666635012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21053666643 - 2¹⁴ = 21053650259 is a prime.

It is a super-2 number, since 2×21053666643² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21053666595 and 21053666604.

It is not an unprimeable number, because it can be changed into a prime (21053666633) 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, 197773 + ... + 284993.

It is an arithmetic number, because the mean of its divisors is an integer number (1858090266).

Almost surely, 2^21053666643 is an apocalyptic number.

21053666643 is a deficient number, since it is larger than the sum of its proper divisors (8675777613).

21053666643 is a wasteful number, since it uses less digits than its factorization.

21053666643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91974.

The product of its (nonzero) digits is 466560, while the sum is 42.

The spelling of 21053666643 in words is "twenty-one billion, fifty-three million, six hundred sixty-six thousand, six hundred forty-three".