20857649551 has 8 divisors (see below), whose sum is σ = 21960694400. Its totient is φ = 19755132120.

The previous prime is 20857649543. The next prime is 20857649609. The reversal of 20857649551 is 15594675802.

It is a happy number.

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 20857649551 - 2³ = 20857649543 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 (20857649251) 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, 49341 + ... + 210118.

It is an arithmetic number, because the mean of its divisors is an integer number (2745086800).

Almost surely, 2^20857649551 is an apocalyptic number.

20857649551 is a deficient number, since it is larger than the sum of its proper divisors (1103044849).

20857649551 is a wasteful number, since it uses less digits than its factorization.

20857649551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263709.

The product of its (nonzero) digits is 3024000, while the sum is 52.

The spelling of 20857649551 in words is "twenty billion, eight hundred fifty-seven million, six hundred forty-nine thousand, five hundred fifty-one".