51515661 has 16 divisors (see below), whose sum is σ = 73185984. Its totient is φ = 32120064.

The previous prime is 51515657. The next prime is 51515671. The reversal of 51515661 is 16651515.

It is not a de Polignac number, because 51515661 - 2² = 51515657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51515621) 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, 5215 + ... + 11411.

It is an arithmetic number, because the mean of its divisors is an integer number (4574124).

Almost surely, 2^51515661 is an apocalyptic number.

51515661 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

51515661 is a deficient number, since it is larger than the sum of its proper divisors (21670323).

51515661 is a wasteful number, since it uses less digits than its factorization.

51515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6380.

The product of its digits is 4500, while the sum is 30.

The square root of 51515661 is about 7177.4411178358. The cubic root of 51515661 is about 372.0886524174.

The spelling of 51515661 in words is "fifty-one million, five hundred fifteen thousand, six hundred sixty-one".