21403207 has 16 divisors (see below), whose sum is σ = 25222912. Its totient is φ = 17781120.

The previous prime is 21403199. The next prime is 21403211. The reversal of 21403207 is 70230412.

It is not a de Polignac number, because 21403207 - 2³ = 21403199 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406207) 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, 63343 + ... + 63679.

It is an arithmetic number, because the mean of its divisors is an integer number (1576432).

Almost surely, 2^21403207 is an apocalyptic number.

21403207 is a deficient number, since it is larger than the sum of its proper divisors (3819705).

21403207 is a wasteful number, since it uses less digits than its factorization.

21403207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 598.

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 21403207 is about 4626.3600162547. The cubic root of 21403207 is about 277.6469778438.

Adding to 21403207 its reverse (70230412), we get a palindrome (91633619).

The spelling of 21403207 in words is "twenty-one million, four hundred three thousand, two hundred seven".