647140021 has 4 divisors (see below), whose sum is σ = 705970944. Its totient is φ = 588309100.

The previous prime is 647140009. The next prime is 647140049. The reversal of 647140021 is 120041746.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 647140021 - 2⁵ = 647139989 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 (647140421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29415445 + ... + 29415466.

It is an arithmetic number, because the mean of its divisors is an integer number (176492736).

Almost surely, 2^647140021 is an apocalyptic number.

It is an amenable number.

647140021 is a deficient number, since it is larger than the sum of its proper divisors (58830923).

647140021 is a wasteful number, since it uses less digits than its factorization.

647140021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58830922.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 647140021 is about 25438.9469318209. The cubic root of 647140021 is about 864.9667627310.

Adding to 647140021 its reverse (120041746), we get a palindrome (767181767).

The spelling of 647140021 in words is "six hundred forty-seven million, one hundred forty thousand, twenty-one".