21473421 has 16 divisors (see below), whose sum is σ = 30842880. Its totient is φ = 13250160.

The previous prime is 21473393. The next prime is 21473423. The reversal of 21473421 is 12437412.

It is a happy number.

It is not a de Polignac number, because 21473421 - 2⁷ = 21473293 is a prime.

It is a super-2 number, since 2×21473421² = 922215618886482, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21473391 and 21473400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21473423) 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, 2881 + ... + 7158.

It is an arithmetic number, because the mean of its divisors is an integer number (1927680).

Almost surely, 2^21473421 is an apocalyptic number.

It is an amenable number.

21473421 is a deficient number, since it is larger than the sum of its proper divisors (9369459).

21473421 is a wasteful number, since it uses less digits than its factorization.

21473421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10096.

The product of its digits is 1344, while the sum is 24.

The square root of 21473421 is about 4633.9422741333. The cubic root of 21473421 is about 277.9502567866.

The spelling of 21473421 in words is "twenty-one million, four hundred seventy-three thousand, four hundred twenty-one".