21670900 has 36 divisors (see below), whose sum is σ = 48305068. Its totient is φ = 8432640.

The previous prime is 21670897. The next prime is 21670933. The reversal of 21670900 is 907612.

It can be written as a sum of positive squares in 6 ways, for example, as 2696164 + 18974736 = 1642^2 + 4356^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 772 + ... + 6628.

Almost surely, 2^21670900 is an apocalyptic number.

21670900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21670900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24152534).

21670900 is an abundant number, since it is smaller than the sum of its proper divisors (26634168).

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

21670900 is a wasteful number, since it uses less digits than its factorization.

21670900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5908 (or 5901 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21670900 is about 4655.2013919915. The cubic root of 21670900 is about 278.7997089388.

The spelling of 21670900 in words is "twenty-one million, six hundred seventy thousand, nine hundred".