661251398 has 4 divisors (see below), whose sum is σ = 991877100. Its totient is φ = 330625698.

The previous prime is 661251379. The next prime is 661251427. The reversal of 661251398 is 893152166.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×661251398² = 874506822713908808, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165312848 + ... + 165312851.

It is an arithmetic number, because the mean of its divisors is an integer number (247969275).

Almost surely, 2^661251398 is an apocalyptic number.

661251398 is a deficient number, since it is larger than the sum of its proper divisors (330625702).

661251398 is a wasteful number, since it uses less digits than its factorization.

661251398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330625701.

The product of its digits is 77760, while the sum is 41.

The square root of 661251398 is about 25714.8089240422. The cubic root of 661251398 is about 871.2086947518.

The spelling of 661251398 in words is "six hundred sixty-one million, two hundred fifty-one thousand, three hundred ninety-eight".