20321055551 has 8 divisors (see below), whose sum is σ = 21086404608. Its totient is φ = 19562571000.

The previous prime is 20321055533. The next prime is 20321055583. The reversal of 20321055551 is 15555012302.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20321055551 - 2⁶ = 20321055487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20321055851) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1710095 + ... + 1721936.

It is an arithmetic number, because the mean of its divisors is an integer number (2635800576).

Almost surely, 2^20321055551 is an apocalyptic number.

20321055551 is a deficient number, since it is larger than the sum of its proper divisors (765349057).

20321055551 is a wasteful number, since it uses less digits than its factorization.

20321055551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3432253.

The product of its (nonzero) digits is 7500, while the sum is 29.

Adding to 20321055551 its reverse (15555012302), we get a palindrome (35876067853).

The spelling of 20321055551 in words is "twenty billion, three hundred twenty-one million, fifty-five thousand, five hundred fifty-one".