20661620525 has 72 divisors (see below), whose sum is σ = 32197001760. Its totient is φ = 13036947840.

The previous prime is 20661620503. The next prime is 20661620527. The reversal of 20661620525 is 52502616602.

It is not a de Polignac number, because 20661620525 - 2⁶ = 20661620461 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661620527) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5524106 + ... + 5527844.

It is an arithmetic number, because the mean of its divisors is an integer number (447180580).

Almost surely, 2^20661620525 is an apocalyptic number.

20661620525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20661620525 is a deficient number, since it is larger than the sum of its proper divisors (11535381235).

20661620525 is a wasteful number, since it uses less digits than its factorization.

20661620525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4123 (or 4111 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 20661620525 in words is "twenty billion, six hundred sixty-one million, six hundred twenty thousand, five hundred twenty-five".