661663025 has 12 divisors (see below), whose sum is σ = 827726412. Its totient is φ = 524643840.

The previous prime is 661663007. The next prime is 661663033. The reversal of 661663025 is 520366166.

It can be written as a sum of positive squares in 6 ways, for example, as 184633744 + 477029281 = 13588^2 + 21841^2 .

It is not a de Polignac number, because 661663025 - 2²⁴ = 644885809 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 114284 + ... + 119933.

It is an arithmetic number, because the mean of its divisors is an integer number (68977201).

Almost surely, 2^661663025 is an apocalyptic number.

It is an amenable number.

661663025 is a deficient number, since it is larger than the sum of its proper divisors (166063387).

661663025 is a wasteful number, since it uses less digits than its factorization.

661663025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234340 (or 234335 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 661663025 is about 25722.8113743424. The cubic root of 661663025 is about 871.3894321821.

The spelling of 661663025 in words is "six hundred sixty-one million, six hundred sixty-three thousand, twenty-five".