21999716 has 6 divisors (see below), whose sum is σ = 38499510. Its totient is φ = 10999856.

The previous prime is 21999689. The next prime is 21999721. The reversal of 21999716 is 61799912.

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 5271616 = 4090^2 + 2296^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2749961 + ... + 2749968.

It is an arithmetic number, because the mean of its divisors is an integer number (6416585).

Almost surely, 2^21999716 is an apocalyptic number.

It is an amenable number.

21999716 is a deficient number, since it is larger than the sum of its proper divisors (16499794).

21999716 is a wasteful number, since it uses less digits than its factorization.

21999716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5499933 (or 5499931 counting only the distinct ones).

The product of its digits is 61236, while the sum is 44.

The square root of 21999716 is about 4690.3854852240. The cubic root of 21999716 is about 280.2027273343.

The spelling of 21999716 in words is "twenty-one million, nine hundred ninety-nine thousand, seven hundred sixteen".