21557056011 has 16 divisors (see below), whose sum is σ = 29739951360. Its totient is φ = 13872968480.

The previous prime is 21557055983. The next prime is 21557056013. The reversal of 21557056011 is 11065075512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21557056011 - 2¹⁹ = 21556531723 is a prime.

It is a super-2 number, since 2×21557056011² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21557056013) 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, 454426 + ... + 499616.

It is an arithmetic number, because the mean of its divisors is an integer number (1858746960).

Almost surely, 2^21557056011 is an apocalyptic number.

21557056011 is a deficient number, since it is larger than the sum of its proper divisors (8182895349).

21557056011 is a wasteful number, since it uses less digits than its factorization.

21557056011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50706.

The product of its (nonzero) digits is 10500, while the sum is 33.

The spelling of 21557056011 in words is "twenty-one billion, five hundred fifty-seven million, fifty-six thousand, eleven".