21996749 has 8 divisors (see below), whose sum is σ = 22545432. Its totient is φ = 21453120.

The previous prime is 21996731. The next prime is 21996757. The reversal of 21996749 is 94769912.

It can be written as a sum of positive squares in 4 ways, for example, as 75625 + 21921124 = 275^2 + 4682^2 .

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 21996749 - 2⁸ = 21996493 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 (21996449) 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, 8447 + ... + 10739.

It is an arithmetic number, because the mean of its divisors is an integer number (2818179).

Almost surely, 2^21996749 is an apocalyptic number.

It is an amenable number.

21996749 is a deficient number, since it is larger than the sum of its proper divisors (548683).

21996749 is a wasteful number, since it uses less digits than its factorization.

21996749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2527.

The product of its digits is 244944, while the sum is 47.

The square root of 21996749 is about 4690.0691892551. The cubic root of 21996749 is about 280.1901302192.

The spelling of 21996749 in words is "twenty-one million, nine hundred ninety-six thousand, seven hundred forty-nine".