21450407 has 4 divisors (see below), whose sum is σ = 23400456. Its totient is φ = 19500360.

The previous prime is 21450389. The next prime is 21450431. The reversal of 21450407 is 70405412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21450407 - 2¹² = 21446311 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 (21450707) 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, 975008 + ... + 975029.

It is an arithmetic number, because the mean of its divisors is an integer number (5850114).

Almost surely, 2^21450407 is an apocalyptic number.

21450407 is a deficient number, since it is larger than the sum of its proper divisors (1950049).

21450407 is a wasteful number, since it uses less digits than its factorization.

21450407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1950048.

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21450407 is about 4631.4584096157. The cubic root of 21450407 is about 277.8509241621.

Adding to 21450407 its reverse (70405412), we get a palindrome (91855819).

The spelling of 21450407 in words is "twenty-one million, four hundred fifty thousand, four hundred seven".