64781661 has 32 divisors (see below), whose sum is σ = 102629376. Its totient is φ = 35568000.

The previous prime is 64781653. The next prime is 64781669. The reversal of 64781661 is 16618746.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (64781653) and next prime (64781669).

It is not a de Polignac number, because 64781661 - 2³ = 64781653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64781669) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 124081 + ... + 124601.

It is an arithmetic number, because the mean of its divisors is an integer number (3207168).

Almost surely, 2^64781661 is an apocalyptic number.

It is an amenable number.

64781661 is a deficient number, since it is larger than the sum of its proper divisors (37847715).

64781661 is a wasteful number, since it uses less digits than its factorization.

64781661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 753.

The product of its digits is 48384, while the sum is 39.

The square root of 64781661 is about 8048.7055480990. The cubic root of 64781661 is about 401.6218753296.

The spelling of 64781661 in words is "sixty-four million, seven hundred eighty-one thousand, six hundred sixty-one".