21481605 has 80 divisors (see below), whose sum is σ = 41817600. Its totient is φ = 10523520.

The previous prime is 21481597. The next prime is 21481613. The reversal of 21481605 is 50618412.

It is an interprime number because it is at equal distance from previous prime (21481597) and next prime (21481613).

It is not a de Polignac number, because 21481605 - 2³ = 21481597 is a prime.

It is a super-2 number, since 2×21481605² = 922918706752050, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 364066 + ... + 364124.

It is an arithmetic number, because the mean of its divisors is an integer number (522720).

Almost surely, 2^21481605 is an apocalyptic number.

It is an amenable number.

21481605 is a deficient number, since it is larger than the sum of its proper divisors (20335995).

21481605 is a wasteful number, since it uses less digits than its factorization.

21481605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 127 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21481605 is about 4634.8252394238. The cubic root of 21481605 is about 277.9855633170.

The spelling of 21481605 in words is "twenty-one million, four hundred eighty-one thousand, six hundred five".