21012397 has 8 divisors (see below), whose sum is σ = 24105600. Its totient is φ = 17942064.

The previous prime is 21012373. The next prime is 21012401. The reversal of 21012397 is 79321012.

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

It is a de Polignac number, because none of the positive numbers 2^k-21012397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3697 + ... + 7462.

It is an arithmetic number, because the mean of its divisors is an integer number (3013200).

Almost surely, 2^21012397 is an apocalyptic number.

It is an amenable number.

21012397 is a deficient number, since it is larger than the sum of its proper divisors (3093203).

21012397 is a wasteful number, since it uses less digits than its factorization.

21012397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11435.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21012397 is about 4583.9281189827. The cubic root of 21012397 is about 275.9466964555.

The spelling of 21012397 in words is "twenty-one million, twelve thousand, three hundred ninety-seven".