21052997 has 8 divisors (see below), whose sum is σ = 24552000. Its totient is φ = 18045132.

The previous prime is 21052979. The next prime is 21053009. The reversal of 21052997 is 79925012.

It is not a de Polignac number, because 21052997 - 2¹² = 21048901 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 (21052907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30347 + ... + 31032.

It is an arithmetic number, because the mean of its divisors is an integer number (3069000).

Almost surely, 2^21052997 is an apocalyptic number.

It is an amenable number.

21052997 is a deficient number, since it is larger than the sum of its proper divisors (3499003).

21052997 is an frugal number, since it uses more digits than its factorization.

21052997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61400 (or 61386 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 35.

The square root of 21052997 is about 4588.3544980744. The cubic root of 21052997 is about 276.1243095074.

The spelling of 21052997 in words is "twenty-one million, fifty-two thousand, nine hundred ninety-seven".