21699901 has 2 divisors, whose sum is σ = 21699902. Its totient is φ = 21699900.

The previous prime is 21699883. The next prime is 21700001. The reversal of 21699901 is 10999612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15444900 + 6255001 = 3930^2 + 2501^2 .

It is a cyclic number.

It is not a de Polignac number, because 21699901 - 2⁵ = 21699869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21699401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10849950 + 10849951.

It is an arithmetic number, because the mean of its divisors is an integer number (10849951).

Almost surely, 2^21699901 is an apocalyptic number.

It is an amenable number.

21699901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21699901 is an equidigital number, since it uses as much as digits as its factorization.

21699901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 21699901 is about 4658.3152533937. The cubic root of 21699901 is about 278.9240210540.

The spelling of 21699901 in words is "twenty-one million, six hundred ninety-nine thousand, nine hundred one".