21424137 has 16 divisors (see below), whose sum is σ = 33264000. Its totient is φ = 12010752.

The previous prime is 21424129. The next prime is 21424159. The reversal of 21424137 is 73142412.

It is a happy number.

It is not a de Polignac number, because 21424137 - 2³ = 21424129 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21420137) 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, 8512 + ... + 10737.

It is an arithmetic number, because the mean of its divisors is an integer number (2079000).

Almost surely, 2^21424137 is an apocalyptic number.

It is an amenable number.

21424137 is a deficient number, since it is larger than the sum of its proper divisors (11839863).

21424137 is a wasteful number, since it uses less digits than its factorization.

21424137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19312.

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

The square root of 21424137 is about 4628.6215010519. The cubic root of 21424137 is about 277.7374511710.

Adding to 21424137 its reverse (73142412), we get a palindrome (94566549).

The spelling of 21424137 in words is "twenty-one million, four hundred twenty-four thousand, one hundred thirty-seven".