21407530 has 8 divisors (see below), whose sum is σ = 38533572. Its totient is φ = 8563008.

The previous prime is 21407527. The next prime is 21407531. The reversal of 21407530 is 3570412.

It can be written as a sum of positive squares in 2 ways, for example, as 18688329 + 2719201 = 4323^2 + 1649^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×21407530³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21407531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1070367 + ... + 1070386.

Almost surely, 2^21407530 is an apocalyptic number.

21407530 is a deficient number, since it is larger than the sum of its proper divisors (17126042).

21407530 is a wasteful number, since it uses less digits than its factorization.

21407530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2140760.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21407530 is about 4626.8272066287. The cubic root of 21407530 is about 277.6656695456.

Adding to 21407530 its reverse (3570412), we get a palindrome (24977942).

The spelling of 21407530 in words is "twenty-one million, four hundred seven thousand, five hundred thirty".