642951 has 8 divisors (see below), whose sum is σ = 952560. Its totient is φ = 428616.

The previous prime is 642947. The next prime is 642953. The reversal of 642951 is 159246.

It is not a de Polignac number, because 642951 - 2² = 642947 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 23813 = 642951 / (6 + 4 + 2 + 9 + 5 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642953) 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, 11880 + ... + 11933.

It is an arithmetic number, because the mean of its divisors is an integer number (119070).

2⁶⁴²⁹⁵¹ is an apocalyptic number.

642951 is a deficient number, since it is larger than the sum of its proper divisors (309609).

642951 is a wasteful number, since it uses less digits than its factorization.

642951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23822 (or 23816 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 642951 is about 801.8422538131. The cubic root of 642951 is about 86.3096373933.

The spelling of 642951 in words is "six hundred forty-two thousand, nine hundred fifty-one".