6561649542 has 32 divisors (see below), whose sum is σ = 15004288512. Its totient is φ = 1873977984.

The previous prime is 6561649537. The next prime is 6561649561. The reversal of 6561649542 is 2459461656.

It is a junction number, because it is equal to n+sod(n) for n = 6561649491 and 6561649500.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73918 + ... + 136334.

It is an arithmetic number, because the mean of its divisors is an integer number (468884016).

Almost surely, 2^6561649542 is an apocalyptic number.

6561649542 is an abundant number, since it is smaller than the sum of its proper divisors (8442638970).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6561649542 is a wasteful number, since it uses less digits than its factorization.

6561649542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64932.

The product of its digits is 1555200, while the sum is 48.

The square root of 6561649542 is about 81004.0094192874. The cubic root of 6561649542 is about 1872.1372174830.

The spelling of 6561649542 in words is "six billion, five hundred sixty-one million, six hundred forty-nine thousand, five hundred forty-two".