21354670997 has 4 divisors (see below), whose sum is σ = 23296004736. Its totient is φ = 19413337260.

The previous prime is 21354670993. The next prime is 21354671021. The reversal of 21354670997 is 79907645312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21354670997 - 2² = 21354670993 is a prime.

It is a super-2 number, since 2×21354670997² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21354670993) 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, 970666853 + ... + 970666874.

It is an arithmetic number, because the mean of its divisors is an integer number (5824001184).

Almost surely, 2^21354670997 is an apocalyptic number.

It is an amenable number.

21354670997 is a deficient number, since it is larger than the sum of its proper divisors (1941333739).

21354670997 is a wasteful number, since it uses less digits than its factorization.

21354670997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1941333738.

The product of its (nonzero) digits is 2857680, while the sum is 53.

The spelling of 21354670997 in words is "twenty-one billion, three hundred fifty-four million, six hundred seventy thousand, nine hundred ninety-seven".