661563770 has 16 divisors (see below), whose sum is σ = 1360931328. Its totient is φ = 226821840.

The previous prime is 661563739. The next prime is 661563787. The reversal of 661563770 is 77365166.

It is a super-2 number, since 2×661563770² = 875333243553225800, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4725386 + ... + 4725525.

It is an arithmetic number, because the mean of its divisors is an integer number (85058208).

Almost surely, 2^661563770 is an apocalyptic number.

661563770 is an abundant number, since it is smaller than the sum of its proper divisors (699367558).

661563770 is a wasteful number, since it uses less digits than its factorization.

661563770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9450925.

The product of its (nonzero) digits is 158760, while the sum is 41.

The square root of 661563770 is about 25720.8819833224. The cubic root of 661563770 is about 871.3458580968.

The spelling of 661563770 in words is "six hundred sixty-one million, five hundred sixty-three thousand, seven hundred seventy".