21999745 has 8 divisors (see below), whose sum is σ = 26558784. Its totient is φ = 17493744.

The previous prime is 21999737. The next prime is 21999763. The reversal of 21999745 is 54799912.

It is a happy number.

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 21999745 - 2³ = 21999737 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21999695 and 21999704.

It is an unprimeable number.

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, 12339 + ... + 14008.

It is an arithmetic number, because the mean of its divisors is an integer number (3319848).

Almost surely, 2^21999745 is an apocalyptic number.

It is an amenable number.

21999745 is a deficient number, since it is larger than the sum of its proper divisors (4559039).

21999745 is a wasteful number, since it uses less digits than its factorization.

21999745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26519.

The product of its digits is 204120, while the sum is 46.

The square root of 21999745 is about 4690.3885766533. The cubic root of 21999745 is about 280.2028504553.

The spelling of 21999745 in words is "twenty-one million, nine hundred ninety-nine thousand, seven hundred forty-five".