20506501557 has 24 divisors (see below), whose sum is σ = 30171847680. Its totient is φ = 13417293120.

The previous prime is 20506501553. The next prime is 20506501559. The reversal of 20506501557 is 75510560502.

It is a happy number.

20506501557 is a `hidden beast` number, since 2 + 0 + 50 + 6 + 50 + 1 + 557 = 666.

It is not a de Polignac number, because 20506501557 - 2² = 20506501553 is a prime.

It is a super-2 number, since 2×20506501557² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20506501553) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 296332 + ... + 358922.

It is an arithmetic number, because the mean of its divisors is an integer number (1257160320).

Almost surely, 2^20506501557 is an apocalyptic number.

It is an amenable number.

20506501557 is a deficient number, since it is larger than the sum of its proper divisors (9665346123).

20506501557 is a wasteful number, since it uses less digits than its factorization.

20506501557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63273 (or 63270 counting only the distinct ones).

The product of its (nonzero) digits is 52500, while the sum is 36.

The spelling of 20506501557 in words is "twenty billion, five hundred six million, five hundred one thousand, five hundred fifty-seven".