21751146 has 64 divisors (see below), whose sum is σ = 51287040. Its totient is φ = 6819120.

The previous prime is 21751139. The next prime is 21751157. The reversal of 21751146 is 64115712.

It is a happy number.

It is a super-2 number, since 2×21751146² = 946224704626632, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 102981 + ... + 103191.

It is an arithmetic number, because the mean of its divisors is an integer number (801360).

Almost surely, 2^21751146 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21751146, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25643520).

21751146 is an abundant number, since it is smaller than the sum of its proper divisors (29535894).

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

21751146 is a wasteful number, since it uses less digits than its factorization.

21751146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 322 counting only the distinct ones).

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

The square root of 21751146 is about 4663.8123890225. The cubic root of 21751146 is about 279.1434110674.

Adding to 21751146 its reverse (64115712), we get a palindrome (85866858).

It can be divided in two parts, 2175 and 1146, that added together give a triangular number (3321 = T₈₁).

The spelling of 21751146 in words is "twenty-one million, seven hundred fifty-one thousand, one hundred forty-six".