20156209920 has 864 divisors, whose sum is σ = 89873731584. Its totient is φ = 4047667200.

The previous prime is 20156209901. The next prime is 20156209939. The reversal of 20156209920 is 2990265102.

It is a happy number.

20156209920 is a `hidden beast` number, since 2 + 0 + 1 + 5 + 620 + 9 + 9 + 20 = 666.

It is an interprime number because it is at equal distance from previous prime (20156209901) and next prime (20156209939).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 27497874 + ... + 27498606.

Almost surely, 2^20156209920 is an apocalyptic number.

20156209920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20156209920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44936865792).

20156209920 is an abundant number, since it is smaller than the sum of its proper divisors (69717521664).

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

20156209920 is a wasteful number, since it uses less digits than its factorization.

20156209920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 809 (or 792 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The spelling of 20156209920 in words is "twenty billion, one hundred fifty-six million, two hundred nine thousand, nine hundred twenty".