20628557 has 2 divisors, whose sum is σ = 20628558. Its totient is φ = 20628556.

The previous prime is 20628529. The next prime is 20628581. The reversal of 20628557 is 75582602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20529961 + 98596 = 4531^2 + 314^2 .

It is a cyclic number.

It is not a de Polignac number, because 20628557 - 2¹⁴ = 20612173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20628757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10314278 + 10314279.

It is an arithmetic number, because the mean of its divisors is an integer number (10314279).

Almost surely, 2^20628557 is an apocalyptic number.

It is an amenable number.

20628557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20628557 is an equidigital number, since it uses as much as digits as its factorization.

20628557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 33600, while the sum is 35.

The square root of 20628557 is about 4541.8671270745. The cubic root of 20628557 is about 274.2560919331.

The spelling of 20628557 in words is "twenty million, six hundred twenty-eight thousand, five hundred fifty-seven".