21751164 has 36 divisors (see below), whose sum is σ = 55279224. Its totient is φ = 7211232.

The previous prime is 21751159. The next prime is 21751187. The reversal of 21751164 is 46115712.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21751164² = 946226270709792, which 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 11 ways as a sum of consecutive naturals, for example, 5559 + ... + 8625.

It is an arithmetic number, because the mean of its divisors is an integer number (1535534).

Almost surely, 2^21751164 is an apocalyptic number.

It is an amenable number.

21751164 is an abundant number, since it is smaller than the sum of its proper divisors (33528060).

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

21751164 is a wasteful number, since it uses less digits than its factorization.

21751164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3274 (or 3269 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 21751164 is about 4663.8143187739. The cubic root of 21751164 is about 279.1434880684.

Adding to 21751164 its reverse (46115712), we get a palindrome (67866876).

The spelling of 21751164 in words is "twenty-one million, seven hundred fifty-one thousand, one hundred sixty-four".