21261870397 has 8 divisors (see below), whose sum is σ = 22035186432. Its totient is φ = 20494020000.

The previous prime is 21261870359. The next prime is 21261870401. The reversal of 21261870397 is 79307816212.

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 21261870397 - 2⁷ = 21261870269 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 (21261870307) 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, 1358488 + ... + 1374049.

It is an arithmetic number, because the mean of its divisors is an integer number (2754398304).

Almost surely, 2^21261870397 is an apocalyptic number.

It is an amenable number.

21261870397 is a deficient number, since it is larger than the sum of its proper divisors (773316035).

21261870397 is a wasteful number, since it uses less digits than its factorization.

21261870397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2732819.

The product of its (nonzero) digits is 254016, while the sum is 46.

The spelling of 21261870397 in words is "twenty-one billion, two hundred sixty-one million, eight hundred seventy thousand, three hundred ninety-seven".