661520015 has 32 divisors (see below), whose sum is σ = 890205120. Its totient is φ = 468550656.

The previous prime is 661519987. The next prime is 661520021. The reversal of 661520015 is 510025166.

It is a cyclic number.

It is not a de Polignac number, because 661520015 - 2¹⁴ = 661503631 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 306179 + ... + 308331.

It is an arithmetic number, because the mean of its divisors is an integer number (27818910).

Almost surely, 2^661520015 is an apocalyptic number.

661520015 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

661520015 is a deficient number, since it is larger than the sum of its proper divisors (228685105).

661520015 is a wasteful number, since it uses less digits than its factorization.

661520015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2363.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 661520015 is about 25720.0313957818. The cubic root of 661520015 is about 871.3266477650.

The spelling of 661520015 in words is "six hundred sixty-one million, five hundred twenty thousand, fifteen".