21355356056657 has 24 divisors (see below), whose sum is σ = 25039063512000. Its totient is φ = 18159644162016.

The previous prime is 21355356056651. The next prime is 21355356056689. The reversal of 21355356056657 is 75665065355312.

It is not a de Polignac number, because 21355356056657 - 2⁴ = 21355356056641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21355356056596 and 21355356056605.

It is not an unprimeable number, because it can be changed into a prime (21355356056651) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4231694 + ... + 7785752.

It is an arithmetic number, because the mean of its divisors is an integer number (1043294313000).

Almost surely, 2^{21355356056657} is an apocalyptic number.

It is an amenable number.

21355356056657 is a deficient number, since it is larger than the sum of its proper divisors (3683707455343).

21355356056657 is a wasteful number, since it uses less digits than its factorization.

21355356056657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3555045 (or 3555038 counting only the distinct ones).

The product of its (nonzero) digits is 85050000, while the sum is 59.

The spelling of 21355356056657 in words is "twenty-one trillion, three hundred fifty-five billion, three hundred fifty-six million, fifty-six thousand, six hundred fifty-seven".