21701399 has 4 divisors (see below), whose sum is σ = 21714264. Its totient is φ = 21688536.

The previous prime is 21701389. The next prime is 21701413. The reversal of 21701399 is 99310712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21701399 - 2¹⁶ = 21635863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3437 + ... + 7430.

It is an arithmetic number, because the mean of its divisors is an integer number (5428566).

Almost surely, 2^21701399 is an apocalyptic number.

21701399 is a deficient number, since it is larger than the sum of its proper divisors (12865).

21701399 is a wasteful number, since it uses less digits than its factorization.

21701399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12864.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21701399 is about 4658.4760383628. The cubic root of 21701399 is about 278.9304391873.

The spelling of 21701399 in words is "twenty-one million, seven hundred one thousand, three hundred ninety-nine".