21290069 has 4 divisors (see below), whose sum is σ = 22542444. Its totient is φ = 20037696.

The previous prime is 21290039. The next prime is 21290083. The reversal of 21290069 is 96009212.

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 19909444 + 1380625 = 4462^2 + 1175^2 .

It is not a de Polignac number, because 21290069 - 2⁸ = 21289813 is a prime.

It is a super-2 number, since 2×21290069² = 906534076049522, which 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 (21290039) 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, 626162 + ... + 626195.

It is an arithmetic number, because the mean of its divisors is an integer number (5635611).

Almost surely, 2^21290069 is an apocalyptic number.

It is an amenable number.

21290069 is a deficient number, since it is larger than the sum of its proper divisors (1252375).

21290069 is a wasteful number, since it uses less digits than its factorization.

21290069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1252374.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 21290069 is about 4614.1162750845. The cubic root of 21290069 is about 277.1568965224.

The spelling of 21290069 in words is "twenty-one million, two hundred ninety thousand, sixty-nine".