21712420 has 24 divisors (see below), whose sum is σ = 46658304. Its totient is φ = 8482656.

The previous prime is 21712393. The next prime is 21712423. The reversal of 21712420 is 2421712.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21712423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11764 + ... + 13483.

It is an arithmetic number, because the mean of its divisors is an integer number (1944096).

Almost surely, 2^21712420 is an apocalyptic number.

21712420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21712420 is an abundant number, since it is smaller than the sum of its proper divisors (24945884).

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

21712420 is a wasteful number, since it uses less digits than its factorization.

21712420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25299 (or 25297 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 21712420 is about 4659.6587857911. The cubic root of 21712420 is about 278.9776492332.

The spelling of 21712420 in words is "twenty-one million, seven hundred twelve thousand, four hundred twenty".