20857998 has 32 divisors (see below), whose sum is σ = 48335616. Its totient is φ = 5876928.

The previous prime is 20857981. The next prime is 20857999. The reversal of 20857998 is 89975802.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 336 + ... + 6467.

It is an arithmetic number, because the mean of its divisors is an integer number (1510488).

Almost surely, 2^20857998 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20857998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24167808).

20857998 is an abundant number, since it is smaller than the sum of its proper divisors (27477618).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20857998 is a wasteful number, since it uses less digits than its factorization.

20857998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6888.

The product of its (nonzero) digits is 362880, while the sum is 48.

The square root of 20857998 is about 4567.0557255195. The cubic root of 20857998 is about 275.2691491634.

The spelling of 20857998 in words is "twenty million, eight hundred fifty-seven thousand, nine hundred ninety-eight".