131225721 has 16 divisors (see below), whose sum is σ = 194477760. Its totient is φ = 78029120.

The previous prime is 131225711. The next prime is 131225747. The reversal of 131225721 is 127522131.

131225721 = T₃₅₈ + T₃₅₉ + ... + T₉₄₀.

It is a cyclic number.

It is not a de Polignac number, because 131225721 - 2⁷ = 131225593 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 131225691 and 131225700.

It is not an unprimeable number, because it can be changed into a prime (131225711) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35766 + ... + 39263.

It is an arithmetic number, because the mean of its divisors is an integer number (12154860).

Almost surely, 2^131225721 is an apocalyptic number.

131225721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

131225721 is a deficient number, since it is larger than the sum of its proper divisors (63252039).

131225721 is a wasteful number, since it uses less digits than its factorization.

131225721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75096.

The product of its digits is 840, while the sum is 24.

The square root of 131225721 is about 11455.3795659507. The cubic root of 131225721 is about 508.1668404913.

Adding to 131225721 its reverse (127522131), we get a palindrome (258747852).

The spelling of 131225721 in words is "one hundred thirty-one million, two hundred twenty-five thousand, seven hundred twenty-one".