21701391 has 8 divisors (see below), whose sum is σ = 28957104. Its totient is φ = 14456640.

The previous prime is 21701389. The next prime is 21701413. The reversal of 21701391 is 19310712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21701391 - 2¹ = 21701389 is a prime.

It is a super-3 number, since 3×21701391³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701371) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5035 + ... + 8291.

It is an arithmetic number, because the mean of its divisors is an integer number (3619638).

Almost surely, 2^21701391 is an apocalyptic number.

21701391 is a deficient number, since it is larger than the sum of its proper divisors (7255713).

21701391 is a wasteful number, since it uses less digits than its factorization.

21701391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5481.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21701391 is about 4658.4751797128. The cubic root of 21701391 is about 278.9304049124.

The spelling of 21701391 in words is "twenty-one million, seven hundred one thousand, three hundred ninety-one".