21503730 has 32 divisors (see below), whose sum is σ = 52488000. Its totient is φ = 5636672.

The previous prime is 21503719. The next prime is 21503731. The reversal of 21503730 is 3730512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21503697 and 21503706.

It is not an unprimeable number, because it can be changed into a prime (21503731) 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, 4305 + ... + 7844.

It is an arithmetic number, because the mean of its divisors is an integer number (1640250).

Almost surely, 2^21503730 is an apocalyptic number.

21503730 is an abundant number, since it is smaller than the sum of its proper divisors (30984270).

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

21503730 is a wasteful number, since it uses less digits than its factorization.

21503730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12218.

The product of its (nonzero) digits is 630, while the sum is 21.

The square root of 21503730 is about 4637.2114465485. The cubic root of 21503730 is about 278.0809677378.

The spelling of 21503730 in words is "twenty-one million, five hundred three thousand, seven hundred thirty".