21040188 has 24 divisors (see below), whose sum is σ = 52870608. Its totient is φ = 6473856.

The previous prime is 21040183. The next prime is 21040199. The reversal of 21040188 is 88104012.

It is a super-2 number, since 2×21040188² = 885379022150688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040183) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67281 + ... + 67592.

It is an arithmetic number, because the mean of its divisors is an integer number (2202942).

Almost surely, 2^21040188 is an apocalyptic number.

It is an amenable number.

21040188 is an abundant number, since it is smaller than the sum of its proper divisors (31830420).

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

21040188 is a wasteful number, since it uses less digits than its factorization.

21040188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134893 (or 134891 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21040188 is about 4586.9584694000. The cubic root of 21040188 is about 276.0682985775.

The spelling of 21040188 in words is "twenty-one million, forty thousand, one hundred eighty-eight".