640120551 has 8 divisors (see below), whose sum is σ = 975421824. Its totient is φ = 365783160.

The previous prime is 640120549. The next prime is 640120573. The reversal of 640120551 is 155021046.

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

It is not a de Polignac number, because 640120551 - 2¹ = 640120549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640120501) 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, 15240945 + ... + 15240986.

It is an arithmetic number, because the mean of its divisors is an integer number (121927728).

Almost surely, 2^640120551 is an apocalyptic number.

640120551 is a deficient number, since it is larger than the sum of its proper divisors (335301273).

640120551 is a wasteful number, since it uses less digits than its factorization.

640120551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30481941.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 640120551 is about 25300.6037674993. The cubic root of 640120551 is about 861.8279807942.

Adding to 640120551 its reverse (155021046), we get a palindrome (795141597).

The spelling of 640120551 in words is "six hundred forty million, one hundred twenty thousand, five hundred fifty-one".