21739900 has 72 divisors (see below), whose sum is σ = 58086560. Its totient is φ = 6877440.

The previous prime is 21739877. The next prime is 21739903. The reversal of 21739900 is 993712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21739903) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7906 + ... + 10294.

Almost surely, 2^21739900 is an apocalyptic number.

21739900 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 21739900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29043280).

21739900 is an abundant number, since it is smaller than the sum of its proper divisors (36346660).

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

21739900 is a wasteful number, since it uses less digits than its factorization.

21739900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2423 (or 2416 counting only the distinct ones).

The product of its (nonzero) digits is 3402, while the sum is 31.

The square root of 21739900 is about 4662.6065671467. The cubic root of 21739900 is about 279.0952942466.

The spelling of 21739900 in words is "twenty-one million, seven hundred thirty-nine thousand, nine hundred".