661245501 has 24 divisors (see below), whose sum is σ = 1043583424. Its totient is φ = 364815360.

The previous prime is 661245493. The next prime is 661245503. The reversal of 661245501 is 105542166.

It is not a de Polignac number, because 661245501 - 2³ = 661245493 is a prime.

It is a super-2 number, since 2×661245501² = 874491225185482002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661245503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1060 + ... + 36381.

Almost surely, 2^661245501 is an apocalyptic number.

It is an amenable number.

661245501 is a deficient number, since it is larger than the sum of its proper divisors (382337923).

661245501 is a wasteful number, since it uses less digits than its factorization.

661245501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37509 (or 37480 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 661245501 is about 25714.6942622307. The cubic root of 661245501 is about 871.2061049486.

Adding to 661245501 its reverse (105542166), we get a palindrome (766787667).

The spelling of 661245501 in words is "six hundred sixty-one million, two hundred forty-five thousand, five hundred one".