21084657 has 16 divisors (see below), whose sum is σ = 31104000. Its totient is φ = 12597200.

The previous prime is 21084649. The next prime is 21084673. The reversal of 21084657 is 75648012.

It is not a de Polignac number, because 21084657 - 2³ = 21084649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21084677) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2157 + ... + 6842.

It is an arithmetic number, because the mean of its divisors is an integer number (1944000).

Almost surely, 2^21084657 is an apocalyptic number.

It is an amenable number.

21084657 is a deficient number, since it is larger than the sum of its proper divisors (10019343).

21084657 is a wasteful number, since it uses less digits than its factorization.

21084657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9084.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21084657 is about 4591.8032405581. The cubic root of 21084657 is about 276.2626542936.

The spelling of 21084657 in words is "twenty-one million, eighty-four thousand, six hundred fifty-seven".