20642557 has 8 divisors (see below), whose sum is σ = 22773240. Its totient is φ = 18589440.

The previous prime is 20642527. The next prime is 20642561. The reversal of 20642557 is 75524602.

It can be written as a sum of positive squares in 4 ways, for example, as 2842596 + 17799961 = 1686^2 + 4219^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20642557 - 2¹⁵ = 20609789 is a prime.

It is a super-2 number, since 2×20642557² = 852230318996498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20642527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18832 + ... + 19897.

It is an arithmetic number, because the mean of its divisors is an integer number (2846655).

Almost surely, 2^20642557 is an apocalyptic number.

It is an amenable number.

20642557 is a deficient number, since it is larger than the sum of its proper divisors (2130683).

20642557 is a wasteful number, since it uses less digits than its factorization.

20642557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38783.

The product of its (nonzero) digits is 16800, while the sum is 31.

The square root of 20642557 is about 4543.4080820459. The cubic root of 20642557 is about 274.3181211064.

The spelling of 20642557 in words is "twenty million, six hundred forty-two thousand, five hundred fifty-seven".