21720192 has 128 divisors (see below), whose sum is σ = 65688000. Its totient is φ = 6303744.

The previous prime is 21720137. The next prime is 21720197. The reversal of 21720192 is 29102712.

21720192 = T₁₃ + T₁₄ + ... + T₅₀₆.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21720197) 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, 94734 + ... + 94962.

Almost surely, 2^21720192 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21720192, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32844000).

21720192 is an abundant number, since it is smaller than the sum of its proper divisors (43967808).

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

21720192 is a wasteful number, since it uses less digits than its factorization.

21720192 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21720192 is about 4660.4926778185. The cubic root of 21720192 is about 279.0109321136.

It can be divided in two parts, 21720 and 192, that added together give a palindrome (21912).

The spelling of 21720192 in words is "twenty-one million, seven hundred twenty thousand, one hundred ninety-two".