21679478501 has 2 divisors, whose sum is σ = 21679478502. Its totient is φ = 21679478500.

The previous prime is 21679478479. The next prime is 21679478519. The reversal of 21679478501 is 10587497612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17835602500 + 3843876001 = 133550^2 + 61999^2 .

It is a cyclic number.

It is not a de Polignac number, because 21679478501 - 2¹⁴ = 21679462117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21679478501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21679478801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10839739250 + 10839739251.

It is an arithmetic number, because the mean of its divisors is an integer number (10839739251).

Almost surely, 2^21679478501 is an apocalyptic number.

It is an amenable number.

21679478501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21679478501 is an equidigital number, since it uses as much as digits as its factorization.

21679478501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 846720, while the sum is 50.

The spelling of 21679478501 in words is "twenty-one billion, six hundred seventy-nine million, four hundred seventy-eight thousand, five hundred one".