21151699 has 4 divisors (see below), whose sum is σ = 21467464. Its totient is φ = 20835936.

The previous prime is 21151687. The next prime is 21151721. The reversal of 21151699 is 99615112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21151699 - 2¹⁷ = 21020627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21151609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157782 + ... + 157915.

It is an arithmetic number, because the mean of its divisors is an integer number (5366866).

Almost surely, 2^21151699 is an apocalyptic number.

21151699 is a deficient number, since it is larger than the sum of its proper divisors (315765).

21151699 is an equidigital number, since it uses as much as digits as its factorization.

21151699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315764.

The product of its digits is 4860, while the sum is 34.

The square root of 21151699 is about 4599.0976288833. The cubic root of 21151699 is about 276.5551514257. Note that the first 3 decimals are identical.

The spelling of 21151699 in words is "twenty-one million, one hundred fifty-one thousand, six hundred ninety-nine".