21420672 has 128 divisors (see below), whose sum is σ = 70143360. Its totient is φ = 5640192.

The previous prime is 21420667. The next prime is 21420677. The reversal of 21420672 is 27602412.

It is an interprime number because it is at equal distance from previous prime (21420667) and next prime (21420677).

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 (21420677) 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, 34638 + ... + 35250.

It is an arithmetic number, because the mean of its divisors is an integer number (547995).

Almost surely, 2^21420672 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 21420672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35071680).

21420672 is an abundant number, since it is smaller than the sum of its proper divisors (48722688).

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

21420672 is a wasteful number, since it uses less digits than its factorization.

21420672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 650 (or 638 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 21420672 is about 4628.2471844101. The cubic root of 21420672 is about 277.7224772166.

The spelling of 21420672 in words is "twenty-one million, four hundred twenty thousand, six hundred seventy-two".