21151404 has 18 divisors (see below), whose sum is σ = 53466140. Its totient is φ = 7050456.

The previous prime is 21151343. The next prime is 21151433. The reversal of 21151404 is 40415112.

21151404 is a `hidden beast` number, since 211 + 51 + 404 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 293734 + ... + 293805.

Almost surely, 2^21151404 is an apocalyptic number.

It is an amenable number.

21151404 is an abundant number, since it is smaller than the sum of its proper divisors (32314736).

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

21151404 is a wasteful number, since it uses less digits than its factorization.

21151404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587549 (or 587544 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21151404 is about 4599.0655572627. The cubic root of 21151404 is about 276.5538657268.

Adding to 21151404 its reverse (40415112), we get a palindrome (61566516).

It can be divided in two parts, 211 and 51404, that added together give a palindrome (51615).

The spelling of 21151404 in words is "twenty-one million, one hundred fifty-one thousand, four hundred four".