20851391900 has 36 divisors (see below), whose sum is σ = 45482005632. Its totient is φ = 8297333760.

The previous prime is 20851391893. The next prime is 20851391909. The reversal of 20851391900 is 919315802.

It is a super-2 number, since 2×20851391900² (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 (20851391909) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 520892 + ... + 559491.

Almost surely, 2^20851391900 is an apocalyptic number.

20851391900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20851391900 is an abundant number, since it is smaller than the sum of its proper divisors (24630613732).

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

20851391900 is a wasteful number, since it uses less digits than its factorization.

20851391900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1080590 (or 1080583 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 38.

The spelling of 20851391900 in words is "twenty billion, eight hundred fifty-one million, three hundred ninety-one thousand, nine hundred".