641721251 has 8 divisors (see below), whose sum is σ = 670696320. Its totient is φ = 613202688.

The previous prime is 641721233. The next prime is 641721271. The reversal of 641721251 is 152127146.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641721251 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641721271) 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, 111251 + ... + 116876.

It is an arithmetic number, because the mean of its divisors is an integer number (83837040).

Almost surely, 2^641721251 is an apocalyptic number.

641721251 is a deficient number, since it is larger than the sum of its proper divisors (28975069).

641721251 is a wasteful number, since it uses less digits than its factorization.

641721251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228253.

The product of its digits is 3360, while the sum is 29.

The square root of 641721251 is about 25332.2176486781. The cubic root of 641721251 is about 862.5457517143.

Adding to 641721251 its reverse (152127146), we get a palindrome (793848397).

The spelling of 641721251 in words is "six hundred forty-one million, seven hundred twenty-one thousand, two hundred fifty-one".