21716651 has 8 divisors (see below), whose sum is σ = 23936304. Its totient is φ = 19537920.

The previous prime is 21716627. The next prime is 21716659. The reversal of 21716651 is 15661712.

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 21716651 - 2⁶ = 21716587 is a prime.

It is a super-2 number, since 2×21716651² = 943225861311602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21716659) 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, 9110 + ... + 11243.

It is an arithmetic number, because the mean of its divisors is an integer number (2992038).

Almost surely, 2^21716651 is an apocalyptic number.

21716651 is a deficient number, since it is larger than the sum of its proper divisors (2219653).

21716651 is a wasteful number, since it uses less digits than its factorization.

21716651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20461.

The product of its digits is 2520, while the sum is 29.

The square root of 21716651 is about 4660.1127668759. The cubic root of 21716651 is about 278.9957690892.

The spelling of 21716651 in words is "twenty-one million, seven hundred sixteen thousand, six hundred fifty-one".