21701857 has 16 divisors (see below), whose sum is σ = 24312960. Its totient is φ = 19274112.

The previous prime is 21701839. The next prime is 21701873. The reversal of 21701857 is 75810712.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21701857 - 2¹¹ = 21699809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21701807) 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, 22693 + ... + 23629.

It is an arithmetic number, because the mean of its divisors is an integer number (1519560).

Almost surely, 2^21701857 is an apocalyptic number.

It is an amenable number.

21701857 is a deficient number, since it is larger than the sum of its proper divisors (2611103).

21701857 is a wasteful number, since it uses less digits than its factorization.

21701857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1032.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 21701857 is about 4658.5251958104. The cubic root of 21701857 is about 278.9324014148.

The spelling of 21701857 in words is "twenty-one million, seven hundred one thousand, eight hundred fifty-seven".