21719405 has 16 divisors (see below), whose sum is σ = 27544320. Its totient is φ = 16414272.

The previous prime is 21719393. The next prime is 21719419. The reversal of 21719405 is 50491712.

It is a cyclic number.

It is not a de Polignac number, because 21719405 - 2⁴ = 21719389 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5222 + ... + 8408.

It is an arithmetic number, because the mean of its divisors is an integer number (1721520).

Almost surely, 2^21719405 is an apocalyptic number.

It is an amenable number.

21719405 is a deficient number, since it is larger than the sum of its proper divisors (5824915).

21719405 is a wasteful number, since it uses less digits than its factorization.

21719405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3268.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 21719405 is about 4660.4082439203. The cubic root of 21719405 is about 279.0075622193.

The spelling of 21719405 in words is "twenty-one million, seven hundred nineteen thousand, four hundred five".