21628877 has 2 divisors, whose sum is σ = 21628878. Its totient is φ = 21628876.

The previous prime is 21628837. The next prime is 21628891. The reversal of 21628877 is 77882612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17422276 + 4206601 = 4174^2 + 2051^2 .

It is a cyclic number.

It is not a de Polignac number, because 21628877 - 2¹² = 21624781 is a prime.

It is a super-2 number, since 2×21628877² = 935616640562258, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21628807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10814438 + 10814439.

It is an arithmetic number, because the mean of its divisors is an integer number (10814439).

Almost surely, 2^21628877 is an apocalyptic number.

It is an amenable number.

21628877 is a deficient number, since it is larger than the sum of its proper divisors (1).

21628877 is an equidigital number, since it uses as much as digits as its factorization.

21628877 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 41.

The square root of 21628877 is about 4650.6856483749. The cubic root of 21628877 is about 278.6193813822.

The spelling of 21628877 in words is "twenty-one million, six hundred twenty-eight thousand, eight hundred seventy-seven".