1261211551 has 8 divisors (see below), whose sum is σ = 1282152240. Its totient is φ = 1240333248.

The previous prime is 1261211531. The next prime is 1261211573. The reversal of 1261211551 is 1551121621.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1261211551 - 2⁵ = 1261211519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261211531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26085 + ... + 56593.

It is an arithmetic number, because the mean of its divisors is an integer number (160269030).

Almost surely, 2^1261211551 is an apocalyptic number.

1261211551 is a deficient number, since it is larger than the sum of its proper divisors (20940689).

1261211551 is an equidigital number, since it uses as much as digits as its factorization.

1261211551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31193.

The product of its digits is 600, while the sum is 25.

The square root of 1261211551 is about 35513.5403895472. The cubic root of 1261211551 is about 1080.4283711635.

The spelling of 1261211551 in words is "one billion, two hundred sixty-one million, two hundred eleven thousand, five hundred fifty-one".