21349240 has 64 divisors (see below), whose sum is σ = 52967520. Its totient is φ = 7744000.

The previous prime is 21349219. The next prime is 21349243. The reversal of 21349240 is 4294312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349243) 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, 53040 + ... + 53440.

Almost surely, 2^21349240 is an apocalyptic number.

21349240 is a gapful number since it is divisible by the number (20) 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 21349240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26483760).

21349240 is an abundant number, since it is smaller than the sum of its proper divisors (31618280).

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

21349240 is a wasteful number, since it uses less digits than its factorization.

21349240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445 (or 419 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21349240 is about 4620.5237798328. The cubic root of 21349240 is about 277.4134242816.

The spelling of 21349240 in words is "twenty-one million, three hundred forty-nine thousand, two hundred forty".