21958900 has 36 divisors (see below), whose sum is σ = 50457708. Its totient is φ = 8266240.

The previous prime is 21958897. The next prime is 21958901. The reversal of 21958900 is 985912.

It can be written as a sum of positive squares in 6 ways, for example, as 19044 + 21939856 = 138^2 + 4684^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21958901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4759 + ... + 8158.

It is an arithmetic number, because the mean of its divisors is an integer number (1401603).

Almost surely, 2^21958900 is an apocalyptic number.

21958900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21958900 is an abundant number, since it is smaller than the sum of its proper divisors (28498808).

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

21958900 is a wasteful number, since it uses less digits than its factorization.

21958900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12948 (or 12941 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 21958900 is about 4686.0324369343. The cubic root of 21958900 is about 280.0293336615.

The spelling of 21958900 in words is "twenty-one million, nine hundred fifty-eight thousand, nine hundred".