261551642 has 16 divisors (see below), whose sum is σ = 428242464. Its totient is φ = 118818000.

The previous prime is 261551617. The next prime is 261551677. The reversal of 261551642 is 246155162.

It is a super-2 number, since 2×261551642² = 136818522865792328, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261551599 and 261551608.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69017 + ... + 72707.

It is an arithmetic number, because the mean of its divisors is an integer number (26765154).

Almost surely, 2^261551642 is an apocalyptic number.

261551642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

261551642 is a deficient number, since it is larger than the sum of its proper divisors (166690822).

261551642 is a wasteful number, since it uses less digits than its factorization.

261551642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6925.

The product of its digits is 14400, while the sum is 32.

The square root of 261551642 is about 16172.5583010234. The cubic root of 261551642 is about 639.5175742691.

The spelling of 261551642 in words is "two hundred sixty-one million, five hundred fifty-one thousand, six hundred forty-two".