649540581 has 16 divisors (see below), whose sum is σ = 871214400. Its totient is φ = 430455168.

The previous prime is 649540571. The next prime is 649540597. The reversal of 649540581 is 185045946.

It is not a de Polignac number, because 649540581 - 2²¹ = 647443429 is a prime.

It is a super-2 number, since 2×649540581² = 843805932731635122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649540511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 692745 + ... + 693681.

It is an arithmetic number, because the mean of its divisors is an integer number (54450900).

Almost surely, 2^649540581 is an apocalyptic number.

It is an amenable number.

649540581 is a deficient number, since it is larger than the sum of its proper divisors (221673819).

649540581 is a wasteful number, since it uses less digits than its factorization.

649540581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2068.

The product of its (nonzero) digits is 172800, while the sum is 42.

The square root of 649540581 is about 25486.0860274778. The cubic root of 649540581 is about 866.0349717506.

The spelling of 649540581 in words is "six hundred forty-nine million, five hundred forty thousand, five hundred eighty-one".