21095691 has 16 divisors (see below), whose sum is σ = 30274848. Its totient is φ = 13017600.

The previous prime is 21095677. The next prime is 21095693. The reversal of 21095691 is 19659012.

It is not a de Polignac number, because 21095691 - 2¹⁹ = 20571403 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21095693) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 280 + ... + 6501.

It is an arithmetic number, because the mean of its divisors is an integer number (1892178).

Almost surely, 2^21095691 is an apocalyptic number.

21095691 is a deficient number, since it is larger than the sum of its proper divisors (9179157).

21095691 is a wasteful number, since it uses less digits than its factorization.

21095691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6862.

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 21095691 is about 4593.0045721728. The cubic root of 21095691 is about 276.3108370479.

The spelling of 21095691 in words is "twenty-one million, ninety-five thousand, six hundred ninety-one".