21240957 has 8 divisors (see below), whose sum is σ = 28354176. Its totient is φ = 14144192.

The previous prime is 21240913. The next prime is 21240971. The reversal of 21240957 is 75904212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21240957 - 2¹² = 21236861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 693 + ... + 6554.

It is an arithmetic number, because the mean of its divisors is an integer number (3544272).

Almost surely, 2^21240957 is an apocalyptic number.

It is an amenable number.

21240957 is a deficient number, since it is larger than the sum of its proper divisors (7113219).

21240957 is an equidigital number, since it uses as much as digits as its factorization.

21240957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8227.

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 21240957 is about 4608.7912732082. The cubic root of 21240957 is about 276.9436169653.

The spelling of 21240957 in words is "twenty-one million, two hundred forty thousand, nine hundred fifty-seven".