21010173657 has 16 divisors (see below), whose sum is σ = 30565563840. Its totient is φ = 12731225600.

The previous prime is 21010173649. The next prime is 21010173671. The reversal of 21010173657 is 75637101012.

It is a cyclic number.

It is not a de Polignac number, because 21010173657 - 2³ = 21010173649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21010173157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 148657 + ... + 253217.

It is an arithmetic number, because the mean of its divisors is an integer number (1910347740).

Almost surely, 2^21010173657 is an apocalyptic number.

It is an amenable number.

21010173657 is a deficient number, since it is larger than the sum of its proper divisors (9555390183).

21010173657 is a wasteful number, since it uses less digits than its factorization.

21010173657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110664.

The product of its (nonzero) digits is 8820, while the sum is 33.

Adding to 21010173657 its reverse (75637101012), we get a palindrome (96647274669).

The spelling of 21010173657 in words is "twenty-one billion, ten million, one hundred seventy-three thousand, six hundred fifty-seven".