21949751 has 8 divisors (see below), whose sum is σ = 22984800. Its totient is φ = 20921472.

The previous prime is 21949747. The next prime is 21949783. The reversal of 21949751 is 15794912.

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 21949751 - 2² = 21949747 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 (21949051) 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, 5675 + ... + 8723.

It is an arithmetic number, because the mean of its divisors is an integer number (2873100).

Almost surely, 2^21949751 is an apocalyptic number.

21949751 is a deficient number, since it is larger than the sum of its proper divisors (1035049).

21949751 is a wasteful number, since it uses less digits than its factorization.

21949751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3385.

The product of its digits is 22680, while the sum is 38.

The square root of 21949751 is about 4685.0561362699. The cubic root of 21949751 is about 279.9904375986.

The spelling of 21949751 in words is "twenty-one million, nine hundred forty-nine thousand, seven hundred fifty-one".