20421816525 has 288 divisors, whose sum is σ = 45023784960. Its totient is φ = 8989056000.

The previous prime is 20421816521. The next prime is 20421816551. The reversal of 20421816525 is 52561812402.

It is not a de Polignac number, because 20421816525 - 2² = 20421816521 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20421816525.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421816521) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 66520422 + ... + 66520728.

Almost surely, 2^20421816525 is an apocalyptic number.

20421816525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20421816525 is an abundant number, since it is smaller than the sum of its proper divisors (24601968435).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20421816525 is a wasteful number, since it uses less digits than its factorization.

20421816525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402 (or 374 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

The spelling of 20421816525 in words is "twenty billion, four hundred twenty-one million, eight hundred sixteen thousand, five hundred twenty-five".