21643016251 has 8 divisors (see below), whose sum is σ = 22919083920. Its totient is φ = 20367276288.

The previous prime is 21643016207. The next prime is 21643016257. The reversal of 21643016251 is 15261034612.

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 21643016251 - 2⁹ = 21643015739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21643016257) 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, 61215 + ... + 216871.

It is an arithmetic number, because the mean of its divisors is an integer number (2864885490).

Almost surely, 2^21643016251 is an apocalyptic number.

21643016251 is a deficient number, since it is larger than the sum of its proper divisors (1276067669).

21643016251 is a wasteful number, since it uses less digits than its factorization.

21643016251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163853.

The product of its (nonzero) digits is 8640, while the sum is 31.

The spelling of 21643016251 in words is "twenty-one billion, six hundred forty-three million, sixteen thousand, two hundred fifty-one".