21628759 has 2 divisors, whose sum is σ = 21628760. Its totient is φ = 21628758.

The previous prime is 21628753. The next prime is 21628799. The reversal of 21628759 is 95782612.

It is an a-pointer prime, because the next prime (21628799) can be obtained adding 21628759 to its sum of digits (40).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21628759 - 2¹⁵ = 21595991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21628753) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10814379 + 10814380.

It is an arithmetic number, because the mean of its divisors is an integer number (10814380).

Almost surely, 2^21628759 is an apocalyptic number.

21628759 is a deficient number, since it is larger than the sum of its proper divisors (1).

21628759 is an equidigital number, since it uses as much as digits as its factorization.

21628759 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 40.

The square root of 21628759 is about 4650.6729620561. The cubic root of 21628759 is about 278.6188746962.

The spelling of 21628759 in words is "twenty-one million, six hundred twenty-eight thousand, seven hundred fifty-nine".