21137424 has 240 divisors, whose sum is σ = 74638080. Its totient is φ = 5080320.

The previous prime is 21137419. The next prime is 21137429. The reversal of 21137424 is 42473112.

21137424 = T₂₃₀ + T₂₃₁ + ... + T₅₁₇.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21137419) and next prime (21137429).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21137394 and 21137403.

It is not an unprimeable number, because it can be changed into a prime (21137429) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 491547 + ... + 491589.

It is an arithmetic number, because the mean of its divisors is an integer number (310992).

Almost surely, 2^21137424 is an apocalyptic number.

21137424 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21137424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37319040).

21137424 is an abundant number, since it is smaller than the sum of its proper divisors (53500656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21137424 is a wasteful number, since it uses less digits than its factorization.

21137424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98 (or 85 counting only the distinct ones).

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

The square root of 21137424 is about 4597.5454320757. The cubic root of 21137424 is about 276.4929229615.

The spelling of 21137424 in words is "twenty-one million, one hundred thirty-seven thousand, four hundred twenty-four".