21081404 has 12 divisors (see below), whose sum is σ = 36929928. Its totient is φ = 10530000.

The previous prime is 21081397. The next prime is 21081413. The reversal of 21081404 is 40418012.

It is a super-2 number, since 2×21081404² = 888851189222432, 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 3 ways as a sum of consecutive naturals, for example, 3179 + ... + 7229.

It is an arithmetic number, because the mean of its divisors is an integer number (3077494).

Almost surely, 2^21081404 is an apocalyptic number.

It is an amenable number.

21081404 is a deficient number, since it is larger than the sum of its proper divisors (15848524).

21081404 is a wasteful number, since it uses less digits than its factorization.

21081404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5356 (or 5354 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21081404 is about 4591.4490087553. The cubic root of 21081404 is about 276.2484460373.

Adding to 21081404 its reverse (40418012), we get a palindrome (61499416).

The spelling of 21081404 in words is "twenty-one million, eighty-one thousand, four hundred four".