21859957 has 4 divisors (see below), whose sum is σ = 24982816. Its totient is φ = 18737100.

The previous prime is 21859949. The next prime is 21859973. The reversal of 21859957 is 75995812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21859957 - 2³ = 21859949 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 (21859907) 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, 1561419 + ... + 1561432.

It is an arithmetic number, because the mean of its divisors is an integer number (6245704).

Almost surely, 2^21859957 is an apocalyptic number.

It is an amenable number.

21859957 is a deficient number, since it is larger than the sum of its proper divisors (3122859).

21859957 is an equidigital number, since it uses as much as digits as its factorization.

21859957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3122858.

The product of its digits is 226800, while the sum is 46.

The square root of 21859957 is about 4675.4632925519. The cubic root of 21859957 is about 279.6081124851.

The spelling of 21859957 in words is "twenty-one million, eight hundred fifty-nine thousand, nine hundred fifty-seven".