21395691 has 32 divisors (see below), whose sum is σ = 33696000. Its totient is φ = 13379904.

The previous prime is 21395677. The next prime is 21395723. The reversal of 21395691 is 19659312.

It is not a de Polignac number, because 21395691 - 2⁵ = 21395659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21395191) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91711 + ... + 91943.

It is an arithmetic number, because the mean of its divisors is an integer number (1053000).

Almost surely, 2^21395691 is an apocalyptic number.

21395691 is a deficient number, since it is larger than the sum of its proper divisors (12300309).

21395691 is a wasteful number, since it uses less digits than its factorization.

21395691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440 (or 434 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 21395691 is about 4625.5476432526. The cubic root of 21395691 is about 277.6144743191.

The spelling of 21395691 in words is "twenty-one million, three hundred ninety-five thousand, six hundred ninety-one".