25777921 has 4 divisors (see below), whose sum is σ = 27760852. Its totient is φ = 23794992.

The previous prime is 25777907. The next prime is 25777931. The reversal of 25777921 is 12977752.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8439025 + 17338896 = 2905^2 + 4164^2 .

It is not a de Polignac number, because 25777921 - 2⁷ = 25777793 is a prime.

It is a super-2 number, since 2×25777921² = 1329002422164482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25777901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 991446 + ... + 991471.

It is an arithmetic number, because the mean of its divisors is an integer number (6940213).

Almost surely, 2^25777921 is an apocalyptic number.

It is an amenable number.

25777921 is a deficient number, since it is larger than the sum of its proper divisors (1982931).

25777921 is a wasteful number, since it uses less digits than its factorization.

25777921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1982930.

The product of its digits is 61740, while the sum is 40.

The square root of 25777921 is about 5077.1961750557. The cubic root of 25777921 is about 295.4037218686.

The spelling of 25777921 in words is "twenty-five million, seven hundred seventy-seven thousand, nine hundred twenty-one".