25438864821 has 32 divisors (see below), whose sum is σ = 36843061248. Its totient is φ = 15551650560.

The previous prime is 25438864807. The next prime is 25438864853. The reversal of 25438864821 is 12846883452.

It is not a de Polignac number, because 25438864821 - 2¹⁸ = 25438602677 is a prime.

It is a super-2 number, since 2×25438864821² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25438864021) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 510736 + ... + 558326.

It is an arithmetic number, because the mean of its divisors is an integer number (1151345664).

Almost surely, 2^25438864821 is an apocalyptic number.

It is an amenable number.

25438864821 is a deficient number, since it is larger than the sum of its proper divisors (11404196427).

25438864821 is a wasteful number, since it uses less digits than its factorization.

25438864821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47881.

The product of its digits is 2949120, while the sum is 51.

The spelling of 25438864821 in words is "twenty-five billion, four hundred thirty-eight million, eight hundred sixty-four thousand, eight hundred twenty-one".