21191064 has 16 divisors (see below), whose sum is σ = 52977720. Its totient is φ = 7063680.

The previous prime is 21191041. The next prime is 21191077. The reversal of 21191064 is 46019112.

It is a super-2 number, since 2×21191064² = 898122386904192, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 882961 = 21191064 / (2 + 1 + 1 + 9 + 1 + 0 + 6 + 4).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 441457 + ... + 441504.

Almost surely, 2^21191064 is an apocalyptic number.

21191064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21191064 is an abundant number, since it is smaller than the sum of its proper divisors (31786656).

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

21191064 is a wasteful number, since it uses less digits than its factorization.

21191064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 882970 (or 882966 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21191064 is about 4603.3752834198. The cubic root of 21191064 is about 276.7266088408.

The spelling of 21191064 in words is "twenty-one million, one hundred ninety-one thousand, sixty-four".