649778021641 has 4 divisors (see below), whose sum is σ = 742603453312. Its totient is φ = 556952589972.

The previous prime is 649778021623. The next prime is 649778021687. The reversal of 649778021641 is 146120877946.

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 649778021641 - 2²¹ = 649775924489 is a prime.

It is a super-2 number, since 2×649778021641² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (649778021041) 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, 46412715825 + ... + 46412715838.

It is an arithmetic number, because the mean of its divisors is an integer number (185650863328).

Almost surely, 2^649778021641 is an apocalyptic number.

It is an amenable number.

649778021641 is a deficient number, since it is larger than the sum of its proper divisors (92825431671).

649778021641 is an equidigital number, since it uses as much as digits as its factorization.

649778021641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92825431670.

The product of its (nonzero) digits is 4064256, while the sum is 55.

The spelling of 649778021641 in words is "six hundred forty-nine billion, seven hundred seventy-eight million, twenty-one thousand, six hundred forty-one".