21253403166 has 16 divisors (see below), whose sum is σ = 42532294800. Its totient is φ = 7080219648.

The previous prime is 21253403131. The next prime is 21253403201. The reversal of 21253403166 is 66130435212.

It is an interprime number because it is at equal distance from previous prime (21253403131) and next prime (21253403201).

It is a super-2 number, since 2×21253403166² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1051171 + ... + 1071198.

It is an arithmetic number, because the mean of its divisors is an integer number (2658268425).

Almost surely, 2^21253403166 is an apocalyptic number.

21253403166 is an abundant number, since it is smaller than the sum of its proper divisors (21278891634).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21253403166 is a wasteful number, since it uses less digits than its factorization.

21253403166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2124043.

The product of its (nonzero) digits is 25920, while the sum is 33.

Adding to 21253403166 its reverse (66130435212), we get a palindrome (87383838378).

The spelling of 21253403166 in words is "twenty-one billion, two hundred fifty-three million, four hundred three thousand, one hundred sixty-six".